The NIC router used to send an ICMP "Destination Unreachable" packet as
response to every unroutable IPv4 packet. However, RFC 1812 section 4.3.2.7
defines certain properties that must be fullfilled by an incoming packet in
order to be answered with this type of ICMP. One requirement is that the packet
is no IPv4 multicast.
This commit prevents sending the mentioned ICMP response for unroutable IPv4
multicasts and instead drops them silently.
Fixes#4563
The NIC router used to add the DNS servers field to DHCP replies regardless of
whether there were DNS servers or not. As reported by a Genode user, the empty
DNS server field irritated at least Windows 10 guests (Vbox 6) that connected
to the NIC router. This resulted in Windows 10 ignoring DHCP offers from the
router with such characteristic.
With this commit adding the DNS server DHCP option is skipped if there are no
DNS servers at the corresponding DHCP server or the domain IP config the server
shall fetch its DNS servers from.
Fixes#4581
Provide additional PCI register information inside the pci-config part
of the devices ROM for clients able to access an Intel graphic card,
namely the GMCH control register content, which contains for instance
the GTT size and stolen memory size.
Ref genodelabs/genode#4578
Implement BIOS handover and Intel resume register update
apart from device driver to circumvent export of PCI
config space to drivers.
Ref genodelabs/genode#4578
The pci_decode has to extract the additional fields from the PCI configuration
space. The platform driver again has to parse and forward the knowledge too.
The PCI BAR indices are exported when info="yes" is set in the policy node for
the corresponding session.
Fixgenodelabs/genode#4577
In overload situations, i.e. when a sender fills up the entire buffer, we land
in situations where the sender receives an ack_avail signal, releases one
packet, allocates and sends a packet and fails to allocate a second packet.
This is especially relevant if the receiver does not batch ack_avail signals
(such as vfs_lwip). In those ping-pong scheduling scenarios, the overhead from
catching the Packet_alloc_failed exception becomes significant. In case of the
NIC router, we will land in an overload situation if the sender is faster than
the receiver. The packet buffer will be filled up at some point and the NIC
router starts to drop packets. For every dropped packet, we currently have to
catch the Packet_alloc_failed exception.
This commit adds a new method alloc_packet_attempt to Packet_stream_source that
has almost the same signature as the older alloc_packet method but returns
an Attempt<Packet_descriptor, Alloc_packet_error> object. As the method already
used the allocator back end exception-less, changes on lower levels were not
needed. Furthermore, the NIC router was modified to use the new exception-less
alloc_packet_attempt instead of alloc_packet.
Ref #4555
Replaces the former implementation of the 'find_by_ip' method at the data
structure for ARP cache entries. This method used to return a reference to the
found object and threw an exception if no matching object was found.
The new implementation doesn't return anything and doesn't throw exceptions. It
takes two lambda arguments instead. One for handling the case that a match was
found with a reference to the matching object as argument and another for
handling the case that no object matches.
This way, expensive exception handling can be avoided and object references
stay in a local scope.
Ref #4555
According to a benchmarking series on Zynq (base-hw) and x260 (base-nova) using
test-nic_perf_router, increasing the 'max_packets_per_signal' has a significant
effect on the packet throughput. By increasing the default value from 32
to 150, we could gain a few hundred Mbit/s. Increasing the value further
does not seem to have such a strong effect, though.
genodelabs/genode#4555
The checksums for forwarded/routed UDP, TCP and ICMP, used to be always
re-calculated from scratch in the NIC router although the router changes only
a few packet fields. This commit replaces the old approach whereever sensible
with an algorithm for incremental checksum updates suggested in RFC 1071.
The goal is to improve router performance.
Ref #4555
The checksums for forwarded/routed IPv4, used to be always re-calculated from
scratch in the NIC router although the router changes only a few packet fields.
This commit replaces the old approach whereever sensible with an algorithm for
incremental checksum updates suggested in RFC 1071. The goal is to improve
router performance.
Ref #4555
We used to use 'unsigned long' for the accumulating variable when calculating
internet checksums. However, 'signed long' is more in accordance with RFC 1071
and will allow us to share the same back end for folding, once we implement
incremental updating of internet checksums.
Ref #4555
Prevent public reflection of the only internally used 'init_sum' argument in
'uint16_t internet_checksum(...)' that, in addition, added a default value to
the function interface.
Ref #4555
When sending an ICMP ECHO reply, the router merely swaps SRC and DST of the
IPv4 header of the corresponding request and these changes cancel each other
out in checksum calculation. Therefore, with this commit, the router skips
updating the IPv4 checksum in this context.
Ref #4555
The router used to update IPv4 checksums when routing via an <ip> rule
despite the fact that it doesn't change any IPv4 header fields in this case.
Ref #4555
The NIC router used to update IPv4 and layer 4 checksums of a packet for each
interface it was sent to (say, all interfaces of the domain the packet was
routed to). However, there was and is no technical reason for not doing it
only once and then iterating over the interfaces with the already updated
packet. This is what this commit does in an intent to raise the router's
performance.
Ref #4555
The NIC router uses the timer for relatively coarse-grained timeouts.
It therefore suffices to update and store the current time when the NIC router
is signalled and use the cached time instead. This prevents frequent
syscalls or RPCs when acquiring the current time for every packet.
genodelabs/genode#4555
The link dissolve timeout is updated for every packet, which leads to
trigger_once() RPCs that only marginally change the scheduled timeout but
significantly slow down the packet throughput.
genodelabs/genode#4555
Using the 'query_buffer_ppgtt()' function allows for retrieving the
virtual address of the buffer in the PPGTT.
This is for components that manage the GPU virtual addresses rather than
the client as is the case with the lima driver.
Issue #4559.
The parent-provides model is destroyed if no <parent-provides> node is
found in the configuration, which resulted in
Warning: list model not empty at destruction time
and leaking memory for the allocated nodes. The commit now explicitly
empties the list model in the destructor of ~Parent_provides_model.
Note, the case is implicitly tested in pkg/test-init by step "denial of
forwarded session request" and <init_config version="empty">.
Thanks to Peter for reporting this issue.
Fixes#4547
Whenever a domain looses all its interfaces or the link state of all attached
interfaces is down at once, the domain potentially moves to another Ethernet
segment and should therefore consider its ARP cache to be outdated.
RFC 826 states that "... If a host moves, any connections initiated by that
host will work, assuming its own address resolution table is cleared when it
moves. ...".
Therefore, this commit introduces clearing the ARP cache and the initially
stated events.
This commit was motivated by an issue with the PinePhone Modem and USB NIC.
On the PinePhone, the Modem has its own OS and acts as direct gateway to the
outer world for the USB NIC that is driven by Genode. However, whenever the
Modem gets restarted, Modem and USB NIC receive a new MAC address. This used
to conflict with the NIC routers ARP entry for the Modem that didn't cease to
be valid.
With this commit, the integrator of such a scenario at least has a convenient
way of fixing this by ensuring that all interfaces at the USB NIC domain go
down when resetting (e.g. by ensuring that the USB NIC is the only interface at
that domain).
Fixes#4558
Replaces the former use of the 'find_by_name' method of the AVL string tree.
This method returned a reference to the found object and threw an exception if
no matching object was found.
The locally implemented replacement doesn't return anything and doesn't throw
exceptions. It takes two lambda arguments instead. One for handling the case
that a match was found with a reference to the matching object as argument and
another for handling the case that no object matches.
This way, expensive exception handling can be avoided and object references
stay in a local scope.
Furthermore, this commit modifies the local wrapper for the insert method of
the AVL string tree, so, that it follows the above mentioned concept as well.
Ref #4536
Replaces the former implementation of the 'find_by_domain' method at the data
structure for NAT rules. This method used to return a reference to the found
object and threw an exception if no matching object was found.
The new implementation doesn't return anything and doesn't throw exceptions. It
takes two lambda arguments instead. One for handling the case that a match was
found with a reference to the matching object as argument and another for
handling the case that no object matches.
This way, expensive exception handling can be avoided and object references
stay in a local scope.
Ref #4536
Replaces the former implementation of the 'find_by_port' method at the data
structure for permit rules. This method used to return a reference to the found
object and threw an exception if no matching object was found.
The new implementation doesn't return anything and doesn't throw exceptions. It
takes two lambda arguments instead. One for handling the case that a match was
found with a reference to the matching object as argument and another for
handling the case that no object matches.
This way, expensive exception handling can be avoided and object references
stay in a local scope.
Furthermore, the commit introduces a convenience wrapper for finding the best
matching pair of transport rule and corresponding permit rule for a given
destination IP and port. This method as well follows the above mentioned
concept.
Ref #4536
Replaces the former implementation of the 'find_longest_prefix_match' method at
the data structure for direct rules. This method used to return a reference to
the found object and threw an exception if no matching object was found.
The new implementation doesn't return anything and doesn't throw exceptions. It
takes two lambda arguments instead. One for handling the case that a match was
found with a reference to the matching object as argument and another for
handling the case that no object matches.
This way, expensive exception handling can be avoided and object references
stay in a local scope.
Ref #4536
Replaces the former implementation of the 'find_longest_prefix_match' method at
the data structure for direct rules. This method used to return a reference to
the found object and threw an exception if no matching object was found.
The new implementation doesn't return anything and doesn't throw exceptions. It
takes two lambda arguments instead. One for handling the case that a match was
found with a reference to the matching object as argument and another for
handling the case that no object matches.
This way, expensive exception handling can be avoided and object references
stay in a local scope.
Ref #4536
Replaces the former implementation of find_by_id at the data structure for
links. This method used to return a reference to the found object and threw an
exception if no matching object was found.
The new implementation doesn't return anything and doesn't throw exceptions. It
takes two lambda arguments instead. One for handling the case that a match was
found with a reference to the matching object as argument and another for
handling the case that no object matches.
This way, expensive exception handling can be avoided and object references
stay in a local scope.
Ref #4536
Just add riscv spec files. The riscv versions should use MMIO transport
as ARM versions do. They also should work fine for riscv_qemu machine
from genode-riscv repository.
acpica and the Intel display driver tries to use the Intel Opregion
simultaneously on Genode, which is not supported nor wanted for IO_MEM region as
which it is handled.
Attempts to remove the access to the region was not successful, since some
SSDT table contains ACPI AML code which is executed regularly and read/write
the Opregion.
The patch adds support to make a copy of the Intel Opregion and report it as
is. The copy was sufficient to make the Intel display driver working to find
and lookup the Intel VBT (video bios table) information to setup all
connectors on a Fujitsu U7411 docking station.
Issue #4531
ACPICA needs access to the host bridge 0:0.0 on Intel, which is also
accessed by the Intel display driver. Since for the Intel display driver the
PCI device is specified in the policy explicitly, the PCI device is filtered
out for the ACPICA driver which uses the policy "ALL".
Issue #4532
As accommodating the session component object is already taken care of
be the root component implementation, remove the remaining redundant
checks.
Fixes#4521.
The hover state is evaluated for the routing of input events. When
routing a touch event, the decision should be based on the most recently
observed touch position. Without this patch, however, the hover state kept
referring to the initial pointer position (screen center) in the absence
of any other motion events.
Issue #4514
* Some fixups for the README
* Make config ROM const when used for the session policies
* Turn Reporter into Expanding_reporter
* Always first register ROM signal handler before parsing it the first time
Outsource parts of the Main object into a common compound object,
common parts of the Makefile description and depot source package.
Fixgenodelabs/genode#4503
* Parse PCI specific information from devices ROM
* Enable DMA, I/O memory and I/O port access dependent on BARs in config space
* Introduce device PD for Nova + IOMMU support
* Enable MSIs if available
* Add PCI specific policy rules
Fixesgenodelabs/genode#4502
Instead of returning an invalid device capability when a device
is (not yet) available, e.g. a PCI device is requested before the
PCI bus got parsed accordingly, we check the device capability
within the Platform::Connection utilities, and register temporarily
an Io_signal_handler to wait for changes of the devices ROM, and
try the device aquisition again. Thereby, simple drivers so not have
to take the burden to do so.
To enable this feature for all drivers, we always have to export a
devices ROM, but limit the information about physical resources
(I/O memory addresses, IRQ numbers, I/O port ranges) to clients with
'info=yes' in their policy description.
Fixgenodelabs/genode#4496
By adding a 'report' node to the platform driver's configuration
one can enable either devices or config reports. The devices
report contains all devices and their detailed state, as well as
whether it is already in use or not. The config report contains
one by one the current configuration of the platform driver.
Moreover, this commit adds a README file describing the facilities
of the platform driver.
Fixgenodelabs/genode#4386
If PCI devices happen to miss complete configuration after boot, the
platform driver supports <pci-fixup> nodes for concrete devices
(specified by bus-device-functions tuples). The
<bar> node instructs the platform driver to remap BAR id 0 to address
0x4017002000, which amends the BIOS configuration and is stringently
required for BARs with address 0.
! <pci-fixup bus="0" device="0x15" function="3">
! <bar id="0" address="0x4017002000"/>
! </pci-fixup>
The issue was discovered with Intel LPSS devices in Fujitsu notebooks.
Fixes#4501
To discharge the generic platform driver from certain PCI bus scanning,
and ACPI + kernel specifics, this commit introduces a new component,
which consumes the acpi drivers report and the platform_info from core
to prepare a devices ROM for the platform driver that contains all
PCI devices and its resources.
Fixgenodelabs/genode#4495
USB Attached SCSI devices might expose a bulk-only interface
as fall-back at interface 0 and alternate setting 0. This commit
allows for probing all alternate settings of the active interface
to be able to use such devices.
The configuration was extended so that in case the device interface
is known beforehand the driver can be configured accordingly.
Fixes#4494.
Since the driver relies on all requests being Nvme::MPS_LOG2 aligned
as advertised in its Block::Info the added check will reject any
misaligned requests (using 'gpt_write' led to an IOMMU write fault).
Issue #4486.
To signal that a device gets used and released by a session
introduce claim, release, and release all callbacks in the
USB interface of the C-API.
Ref genodelabs/genode#4483
Before this commit, the block-request handler was implemented as
Io_signal_handler and, additionally, the USB driver called the
block-request handler on request completion directly on I/O level. This
is generally a bad idea because I/O handlers should avoid to have direct
global side effects. In contrast, application logic should be
implemented in way that it consumes atomic state changes after I/O
completed. Now USB I/O completion locally submits a signal to the
block-request Signal_handler.
The Uplink_test used to end in an uncaucht exception about a failed packet
allocation on several x86_32 platforms.
* Destruct and re-construct the corresponding TX packet allocator during a
link-down-up step in the Uplink test. Fixes the exceptions but results in a
never ending test.
* Decouple the link-down-up steps from the handling of packet stream signals
by simply triggering it with a local periodic timeout of 1 sec period.
This prevents that the Uplink_test never finishes because it destructs the
Uplink connection too often.
* The test finishes not before at least 3 link-down-up steps were executed.
* Replace the Allocator_avl's used for the TX packet allocators of the Nic
and Uplink Connection with the better suited Nic::Packet_allocator.
Ref #4419
The service is merely announced but trying to request a session always causes a
Service_denied exception. This helps in scenarios where the client is
won't open a session anyway but expects the service to be available. This is
considered a temporary solution.
Ref #4419
This patch reverts the vfs-watch-handle creation whenever the subsequent
allocation of the VFS server's 'Watch' object fails. This can happen
when the session RAM or cap quota is depleted.
Fixes#4472
'Platform::Device_pd::attach_dma_mem' may lead to insufficient resources
for meta data, which is reflected to the client via 'Out_of_caps' or
'Out_of_ram'. In case the client upgrades its session the quotas need to
be passed to core as done by
'Platform::Device_pd::Expanding_region_map_client::attach'.
issue #4451
Use 'avail_caps' and 'avail_ram' for resource guards because 'used_caps'
and 'used_ram' do not account for resources given to the platform
driver. This lead to incorrect resource accounting by the GPU
multiplexer.
issue #4451
The calculations of packet_size and packet_count in the block_io() did
not consider rounding errors. This resulted in diverging values over
several bisecting operations (/= 2) and wrongly-size packet allocations
as well as memcpy operations.
Related to #2263 (comments about partial block accesses and
_block_io()).
Fixes#4471
The NIC router used to handle each type of packet-stream signal with a distinct
method in the Interface class. However, merging those methods has advantages.
It ensures that sent packets that were already acknowledged by the counter side
are always released before handling received packets. This frees packet stream
memory which facilitates the potential allocation of response packets while
handling received packets. Furthermore, it simplifies the code and reduces the
number of entry points into the router.
This commit also removes the installation of signal handlers at packet streams
for events that are of no interest for the router (TX-ready-to-ack /
RX-ready-to-submit at NIC sessions and RX-ready-to-ack / TX-ready-to-submit at
Uplink sessions).
Fixes#4470
Whenever the nic_router encounters ARP requests on an interface
that does not have a valid IP config it will ignore them. However,
When increasing the verbosity of the component for diagnostic
purposes the resulting 'Bad network protocol' message is misleading.
Issue #4455.
* Test DHCP RENEW by the test client in the unmanaged variant.
* Add event IDs to log output of test client in order to prevent false positive
result in the managed variant.
* Let managed and unmanaged variant have separate string patterns for
'run_genode_until' because they already had different output and it will
differ even more as we don't want to test DHCP RENEW with the managed
variant.
* Delay first test client DHCP in order to fix unexpected sporadic initial IP
config.
* Remove some unnecessary code from the run script
Fixes#4460
The NIC router did update the IP config of a domain on a completed DHCP
REQUEST but not on completed DHCP RENEW or DHCP REBIND. Thus, it didn't adapt
to "real" DHCP servers (not NIC router servers) that got restarted with a
changed configuration by the means of RENEW/REBIND. The commit fixes this.
Note, that testing this is complicated as we don't have the necessary
infrastructure (we cannot simply use the DHCP server of the NIC router as this
would apply a link down/up sequence in order to let the client restart DHCP)
Ref #4460
by using the io_mem RPC of the platform session instead of parsing the
bar resources manually. This commits avoids and breakage on systems where
the Intel graphic cards just uses 64bits with addresses above 4G.
Issue #4450
Our usb_host driver supports UHCI, OHCI, EHCI, and XHCI host
controllers. The USB4 host interface / Thunderbolt is currently not
supported and must therefore not be passed to the USB host driver.
With this fix, the driver no longer aborts on the Tigerlake notebook and
just skips the out-of-region ACPI table. Issue #4452 is not fixed by
this commit, but in this specific case the table is not used anyway.
Check if there are a least 4 caps + 2MB (heap) + possible buffer size
available before any resource allocation. Only account resources that are
actually used.
issue #4451
The former implementation relied on the behaviour of how the old
intel fb driver requested the pci devices. The new lxkit however actually
really want to have all available pci devices.
Issue #4450
If size is zero, the platform goes out of service by:
[init -> platform_drv] Error: Uncaught exception of type 'Genode::Ram_allocator::Denied'
[init -> platform_drv] Warning: abort called - thread: e
Issue #4450
This patch changes the output format of the trace logger to become
better suitable for human consumption. For example, when instrumenting
the VFS server in Sculpt using the GENODE_TRACE_TSC utility, the
trace logger now generates tabular output as follows.
Report 4
PD "init -> runtime -> arch_vbox6 -> vbox -> " ----------------
Thread "vCPU" at (0,0) total:12909024 recent:989229
Thread "vCPU" at (1,0) total:5643234 recent:786437
PD "init -> runtime -> ahci-0.fs" -----------------------------
Thread "ahci-0.fs" at (0,0) total:910497 recent:6335
Thread "ep" at (0,0) total:0 recent:0
71919692932: TSC process_packets: 8005M (4998 calls, last 4932K)
71921558516: TSC process_packets: 8006M (4999 calls, last 1596K)
71922760220: TSC process_packets: 8007M (5000 calls, last 1006K)
71929853586: TSC process_packets: 8009M (5001 calls, last 1840K)
71931315246: TSC process_packets: 8011M (5002 calls, last 1253K)
72127999920: TSC process_packets: 8016M (5003 calls, last 5606K)
72129568198: TSC process_packets: 8018M (5004 calls, last 1345K)
77161908178: TSC process_packets: 8029M (5005 calls, last 11349K)
77643225736: TSC process_packets: 8029M (5006 calls, last 217K)
89422100594: TSC process_packets: 8035M (5007 calls, last 5656K)
89422123632: TSC process_packets: 8035M (5008 calls, last 1342)
Thread "signal handler" at (0,0) total:36329 recent:3001
Thread "signal_proxy" at (0,0) total:51838 recent:13099
Thread "pdaemon" at (0,0) total:97184 recent:332
Thread "vdrain" at (0,0) total:1266 recent:286
Thread "vrele" at (0,0) total:1904 recent:516
PD "init -> runtime -> nic_drv" -------------------------------
Thread "nic_drv" at (0,0) total:34044 recent:897
Thread "signal handler" at (0,0) total:369 recent:142
...
Subjects that belong to the same PD are grouped together. The formerly
optional affinity and activity options have been removed. Those
information are now unconditionally displayed. The trace entries
belonging to a thread appear as slightly indented.
The patch also updates the coding style, avoiding excessively long
lines.
Issue #4448
This patch reduces repetitive log output by omitting inactive trace
subjects from the log output. The information about all subjects can
still be dumped by setting 'verbose="yes"'.
Issue #4448
This patch splits the creation and updating of monitor objects into two
stages. The creation of a monitor object changes the state of the
associated trace subject. The patch ensures that the new state is
captured by the update of the monitor object.
Issue #4448
This patch makes the trace-subject state as reflected to the trace
monitor more accurate.
Until now, a subject could be in UNTRACED or TRACED state. In reality,
however, there exists an intermediate state after the trace monitor
called 'trace' for the subject but before the subject locally activated
the tracing (done when passing a trace point). This intermediate state
was reflected as UNTRACED. Consequently, threads that never pass a trace
point (e.g., just waiting for I/O) would remain to appear as UNTRACED
even after enabling its tracing by the trace monitor. This is confusing.
This patch replaces the former UNTRACED and TRACED states by three
distinct states:
UNATTACHED prior any call of 'trace'
ATTACHED after a trace monitor called 'trace'
but before the tracing is active
TRACE tracing is active
Fixes#4447
The existing assignment of CPU quotas did not anticipate the dynamic
reconfiguration of init. It merely tracked the available CPU quota by
deducing the consumed amount from a global variable but never
replenished the value. This worked for static scenarios but failed in
situations where components are dynamically re-started.
So far this deficiency remained detected because CPU quotas were not
used in highly dynamic systems like Sculpt OS. However, this has
recently changed by commit "sculpt: assign CPU quotas".
The patch improves the accounting by mirroring the existing handling of
RAM and cap quotas. Note that the CPU-quota accounting is still rather
limited. In particular the dynamic rebalancing is not yet supported.
Issue #4445
With the consolidation of the file-system session's signal handlers
implemented by commit "file_system_session: merge ack and submit sigh",
we can now change the VFS server to produce batches of acknowledgements
before explicitly waking up the client. (in contrast to the traditional
'acknowledge_packet', the new 'try_ack_packet' triggers no signal)
Issue #4388
Split the trace buffer into two partitions in order to prevent overwriting
of entries when the consumer is too slow. See file comment in buffer.h.
genodelabs/genode#4434
This commit simplifies the current implementation by overloading the
length field with a padding indicator in addition to the zero-length
head entry. This simplifies the iteration semantics as it eliminates
the need for determining whether a zero-length entries is the actual
head of the buffer or a padding at the buffer end.
genodelabs/genode#4434
* Unifies the declaration of callbacks which manage driver/client
shared dataspaces
* Move the Linux driver-specific callback implementation to the
lx_emul library from the PC's USB host driver
Fixgenodelabs/genode#4439
* The problem occured only on OKL4, seL4, and L4/Fiasco
* The test used to continue submitting packets regardless of how many were in
flight
* This commit limits the in-flight packets at the Uplink/Nic connections to 40
each
Ref #4419
This commit changes the touch-click filter to adhere the following
sequence:
touch (physical)
press (artifically generated)
release (artificially generated)
release_touch (physical)
This order is important because nitpicker's focus handling takes
press/release events into account. If the release-touch event appears
before the release event, nitpicker subsumes the release-touch event
to the sequence that started with the press event, instead of handling
it as a free-standing event.
Issue #4332
When a device got already acquired by a platform session client, do not
return the same capability again, even if the same platform session
client requested it. Therefore, make doubtful behaviour of client components
visible, and do not have to struggle with Platform::Device instances
instantiated multiple times, which care of the lifetime of the device
capability internally.
Fixgenodelabs/genode#4379
* Switch from the legacy usb_host driver to the new PC version
in recipes and automated tests
* Update documentation snippets
* Remove outdated, unused usb_rndis run-script
Fixgenodelabs/genode#4416
Do not only report devices, but the current configuration of the driver too,
as long as the `report` node in the configuration states it.
Ref genodelabs/genode#4416
To stay consistent with the configuration of the legacy usb_host_drv
and other components as well, do not report USB devices by default,
but when the following XML node is set within the component's
configuration:
<report devices="yes"/>
Ref genodelabs/genode#4416
Adds a function to the USB part of the Genode's C API, to enable
usb_host drivers to acknowledge USB request in client's packet buffer
although they are not assigned to an USB device. The requests are
marked with a "no device" error.
This commit fixes a regression originally solved in genodelabs/genode#4149
Ref genodelabs/genode#4416
XML allows attribute values like <node attr="\"/>. The XML parser
wrongly reflects this case as 'Invalid_syntax'. This behavior stems from
the implicit use of the 'end_of_quote' function, which considers the
sequence of '\"' as a quoted '"' rather than the end of a quoted string.
The patch solves this problem by making the 'end_of_quote' part of
the tokenizer's scanner policy.
The patch removes the 'end_of_quote' function from 'util/string.h'
because it is not universal, and to avoid the ambiguity with
'SCANNER_POLICY::end_of_quote'.
Fixes#4431
The Single_file_system now forwards the
`File_io_service::notify_read_ready` method to the
handle as it already did for most of the other methods.
genodelabs/genode#4394
This reference member is not used anywhere in the code. This prompts
clang to complain about it. Eliminate the member and all the plumbing
associated with it to silence the warning.
Issue #4421
Clang likes to complain when lambdas capture parameters without
actually using them. This patch fixes a couple of such problems in VFS
related os module code.
Issue #4421
* Creates sessions to all supported services of the black hole component
* Test-drives the Event and Capture session with dummy input
* Adds the test to the default list of depot_autopilot.run
* Test-driving the Audio_in and Audio_out sessions is still missing and should
be added via a dedicated commit
Ref #4419
This patch makes nitpicker's "clicked" report useful for the detection
of clicks outside of any client. This is needed in situations where the
dialog should close when clicking outside its screen area. In the new
version, a click outside any client results in a report without a
'label' attribute. Furthermore, the report is augmented by the sequence
number of the click, which allows for freshness checks by the consumer of
the report (i.e., sculpt_manager).
Issue #4398
The functionality of the test-block-client, test-block-server, and
test-block-bench components is now covered by the block_tester
application and the vfs_block server.
Issue #4405
This patch eliminates warnings that occurred as side effect of using the
'Session_policy' utility ("Warning: no policy defined for label...").
The new version uses the 'with_matching_policy' function instead, which
has the nice side effect of simplifying the error handling.
This patch enhances the PD-session interface with the support needed for
user-level device drivers performing DMA. Both RPC functions are
intended for the direct use by the platform driver only. If invoked for
PDs that lack the managing-system role, the operations have no effect.
The 'dma_addr()' RPC function allows the platform driver to request the
DMA address of a given RAM dataspace. It is meant to replace the
'Dataspace::phys_addr' RPC function.
The 'attach_dma' RPC function adds the given dataspace to the device
PD's I/O page table. It replaces the former heuristics of marking DMA
buffers as uncached RAM on x86.
With this patch, the UNCACHED attribute of RAM dataspaces is no longer
used to distinguish DMA buffers from regular RAM dataspaces.
Issue #2243
This patch replaces formerly blocking packet-stream operations by
the explicit use of 'wait_and_dispatch_io_signal' for blocking.
It also removes a misleading comment that promised a fire-and-forget
behavior whereas the implementation relied on blocking I/O anyway.
Issue #4390
The VFS block plugin used to depend on the blocking semantics of the
packet stream's 'get_acked_packet'. This patch replaces this dependency
by the use of 'wait_and_dispatch_one_io_signal'. However, in order to
implement this change, the custom instance of a 'Signal_receiver' had to
be removed as well.
To keep this patch as little invasive as possible, it does not touch the
direct use of the block session's packet stream, which should better be
replaced by the 'Block::Connection::Job' API.
Issue #4390
The zynq_nic_drv follows a zero-copy approach and thus uses the packet
buffers as DMA memory. In order to know when the RX DMA memory can be used
for another packet, a custom ack_avail_handler is needed.
Similarly, packets received from the Uplink session are not copied to a
DMA buffer but to directly passed on as DMA memory. For this purpose,
a a custom packet_avail handler is needed.
genodelabs/genode#4384
This patch replaces the direct use of a file-system session via the
'file_system/util.h' helpers by the VFS using the os/vfs.h API. This
makes the component more flexible while removing the dependence from
read and write utilities of file_system/util.h, which happen to rely on
the (now removed) blocking packet-stream semantics.
Issue #4390
This patch takes precautions against the use of blocking packet-stream
operations like 'submit_packet'.
With the change of issue #4388, the ready-to-submit signals are no
longer implicitly handled. Hence, a call of submit_packet to a
saturated submit queue blocks infinitely.
Issue #4390
* use 'Id_space::apply_any' instead of 'for_each' to destroy session local
buffer objects
* save session capability in session because 'cap()' is not valid in
'Session_component' destructor because it was dissolved before calling
'Root::_destruct_session', the cap is necessary to remove owned
buffers from the EP
issue #4380
Account RAM and CAP resources for GPU sessions and trigger client
upgrades before allocating resources at the multiplexer. This prevents
the multiplexer from running out of resources.
issue #4380
Imagine receiving the signal for an available TX ack or an available RX packet
at the Uplink connection but a later received signal for a link-state change
(to link state "down") at the same connection is handled first and destructs
the Uplink connection before the handling of the former signals. In this case,
the methods 'Uplink_client_base::_conn_tx_handle_ack_avail' and
'Uplink_client_base::_conn_rx_handle_packet_avail' must be guarded against an
unconstructed '_conn' member, but they weren't so far.
Fixes#4384
So far, the generic Uplink connection code considered NIC drivers to transmit
connection RX packets in three different manners. Most of the drivers follow
the "normal" way of transmission with only one driver callback from generic
code. The monolithic USB NIC-driver, however, used to send in a "burst" mode
that required a dedicated path with multiple driver callbacks in the generic
code. And then there were drivers that had a fully custom function for doing
transmissions.
Also for handling connection TX acks, there was a "normal" and a
"custom handler" way.
Today, all NIC drivers in the Genode repos and the Genode-World repo follow the
"normal" way. Therefor, the unused code can be removed.
Ref #4384
This patch equips Sculpt with the ability to customize the system image
in very flexible ways.
All customizable aspects of the image have been relocated from the
former sculpt.run script and the accompanied gems/run/sculpt/ directory
to a new location - the sculpt/ directory - which can exist in any
repository. The directory at repos/gems/sculpt/ serves as reference.
The sculpt directory can host any number of <name>-<board>.sculpt files,
each containing a list of ingredients to be incorporated into the
Sculpt system image. The <name> can be specified to the sculpt.run
script. E.g., the following command refers to the 'default-pc.sculpt'
file:
make run/sculpt KERNEL=nova BOARD=pc SCULPT=default
If no 'SCULPT' argument is supplied, the value 'default' is used.
A .sculpt file refers to a selection of files found at various
subdirectries named after their respective purpose. In particular, There
exists a subdirectory for each file in Sculpt's config fs, like
nitpicker, drivers... The .sculpt file selects the alternative to use
by a simple tag-value notation.
drivers: pc
The supported tags are as follows.
*Optional* selection of /config files. If not specified, those files are
omitted, which prompts Sculpt to manage those configurations
automatically or via the Leitzentrale GUI:
fonts
nic_router
event_filter
wifi
runtime
gpu_drv
Selection of mandatory /config files. If not specified, the respective
'default' alternative will be used.
nitpicker
deploy
fb_drv
clipboard
drivers
numlock_remap
leitzentrale
usb
system
ram_fs
Furthermore, the .sculpt file supports the optional selection of
supplemental content such as a set of launchers.
launches: nano3d system_shell
Another type of content are the set of blessed pubkey/download files
used for installing and verifying software on target.
With the new version, it has become possible to supply a depot with the
the system image. The depot content is assembled according to the 'pkg'
attributes found in launcher files and the selected deploy config.
The resulting depot is incorporated into the system image as 'depot.tar'
archive. It can be supplied to the Sculpt system by mounting it into the
ram fs as done by the 'ram_fs/depot' configuration for the ram fs.
It is possible to add additional boot modules to the system image. There
are two options.
build: <list of targets>
This tag prompts the sculpt.run script to build the specified targets
directly using the Genode build system and add the created artifacts
into the system image as boot modules.
import: <list of depot src or pkg archives>
This tag instructs Sculpt to supply the specifid depot-archive content
as boot modules to the system image. This change eliminates the need for
board-specific pkg/sculpt-<board> archives. The board-specific
specializations can now be placed directly into the respective .sculpt
files by using 'import:'.
To make the use of Sculpt as testbed during development more convenient,
the log output of the drivers, leitzentrale, and runtime subsystems
can be redirected to core using the optional 'LOG=core' argument, e.g.,
make run/sculpt KERNEL=linux BOARD=linux LOG=core
The former pkg/sculpt-installation and pkg/sculpt-installation-pc
archives have been replaced by pkg/sculpt_distribution-pc, which
references the generic pkg/sculpt_distribution archive. Those pkgs are
solely used for publishing / distribution purposes.
Fixes#4369
Fix some trivial cases where the signedness of the constant value does
not match the signedness of type the code expects to see. GCC can be
asked to warn about those by passing Wsign-covnersion flag.
Issue #4354
This comes up when building the code with clang 13. It happens due to
recently enabled Wconversion warning, which in case of clang also
enables implicit-int-conversion warning. The warning reads:
fs_file_system.h:937:44: error: higher order bits are zeroes after
implicit conversion [-Werror,-Wimplicit-int-conversion]
::File_system::Watch_handle fs_handle { -1U };
~~~~~~~~~ ^~~
This can be fixed by properly specifying fs_handle value to be of
unsigned long type.
Issue #4354
Remove '_expected_offset' check on round trip test from RX packet,
because allocators between RX/TX can have different allocation
strategies. Rely on 'pattern' check for RX packets only.
In loopback server alloc size must match actual packet size.
issue #4312
Override 'try_alloc/free' because ethernet frame headers are 14 bytes
(src/dst mac (12) + ethertype (2)) causing the IP header to be 2 byte
aligned, leading to problems on platforms that require load/store
operations to be naturally aligned when reading, for example, 4 byte IP
addresses. Therefore, we align the allocation to 2 bytes, so the IP
header is aligned to 4.
issue #4312
This patch improves the robustness of the CPU-affinity handling.
- The types in base/affinity.h received the accessors
'Location::within(space)' and 'Affinity::valid', which alleviates
the fiddling with coordinates when sanity checking the values,
in init or core.
- The 'Affinity::Location::valid' method got removed because its
meaning was too vague. For sanity checks of affinity configurations,
the new 'within' method is approriate. In cases where only the x,y
values are used for selecting a physical CPU (during thread creation),
the validity check (width*height > 0) was not meaningful anyway.
- The 'Affinity::Location::from_xml' requires a 'Affinity::Space'
as argument because a location always relates to the bounds of
a specific space. This function now implements the selection of
whole rows or columns, which has previously a feature of the
sandbox library only.
- Whenever the sandbox library (init) encounters an invalid affinity
configuration, it prints a warning message as a diagnostic aid.
- A new 'Affinity::unrestricted' function constructs an affinity that
covers the whole affinity space. The named functions clarifies
the meaning over the previous use of the default constructor.
- Core's CPU service denies session requests with an invalid
affinity parameter. Previously, it would fall back to an
unrestricted affinity.
Issue #4300
After VirtIO::Queue refactoring buffers no longer share the same
dataspace as VirtIO rings. This makes optimal buffer calculations a lot
easier. In this case 64 buffers 2kB each will need precisely 128kB of
RAM. Previous value of 2016 will just waste 768b.
Fixed#4347
The key changes in this patch are:
* Buffer allocation is moved into a separate Buffer_pool helper. The
implementation of the buffer allocation strategy does not change.
The helper allocates a single RAM dataspace and splits it in multiple,
equally sized chunks.
* Management of main descriptor ring is enacapsulated in Descriptor_ring
helper class.
* Use separate RAM dataspaces for descriptor rings and buffers.
Previously both of them were packed into a single dataspace. This
might have been more RAM efficient, but IMO it made the code uglier and
harder to understand.
* All of the VirtIO::Queue members are now initialized on the class member
initializer list. This is possible due to previously listed changes.
* Since all VirtIO::Queue members are initalized on member initalizer
list, some additional ones can be marked as const, ex _avail, _used ring
pointers.
* Move descriptor writing code into a common method used by both
write_data and write_data_read_reply members. This avoids some code
duplication between those methods.
* Get rid of request_irq argument that most public VirtIO::Queue methods
accept. None of the existing drivers use it and I doubt this will
change any time soon.
* Use Genode namespace by default in Virtio.
This patch also fixes at least one bug that I discovered while working
on VirtIO block device driver. Namely, when chaining descriptors only the
first descriptor in the chain should be exposed in the available ring.
Issue #4347
Share datastructures for clock, power and reset related configurations
per device. In the generic platform driver component these structures
are kept empty. Driver derivates can fill the clocks settings, power and
reset switches with life. The former Driver::Env gets removed.
Fix#4338
This change of the inner working of the platform driver for ARM allows
clients to have permanent open sessions, as long as a policy node matches
the client. If devices disappear from the policy resp. from the set of
available devices (hotplug), the devices ROM of the session gets updated,
and a corresponding device session gets closed. If the device remains
untouched in the configuration but other devices appeared/disappeared, the
device session is not affected.
Ref #4330
* Only give managing_system permission when all parent nodes of the
corresponding component agree in doing so.
* Move the physical memory constrains heuristic from sandbox library to core
Fix#4335
* Track all caps and ram quotas of the sub-sessions properly
* Release DMA buffers, it is not done implicitely when destroying
the Constrained_ram_allocator
* Do not replenish quota before really releasing memory from
the allocator
Issue #4330
The Session_component must be destroyed before updating the device
model because the Session_component must also release all previously
acquired devices. If the device model is updated before, the devices
might have been removed.
Issue #4330
Pre-allocate all possible type of policy objects as part of the thread meta
state to avoid increased memory consumption due to different policy object
sizes. The cpu_balancer accounts the memory per client and can't forward
potentially occurring out-of-ram exceptions during config-ROM update phases.
Fixes#4333
The commits avoids reading in and allocating memory for all potentially
threads, which are potentially currently not existent (but configured in the
policy beforehand). Instead the policy is read in and evaluated when a thread
is created and policy changes are solely applied to existing/running threads.
By this the commit avoids the increase of memory consumption during the
evaluation of policies during config ROM updates.
Issue #4333
This implements the necessary bits to provide 2D framebuffer support on
top of VirtIO GPU device as implemented in Qemu. I don't know if any
other implementation of this specific device exists.
Compared to the ramfb driver which already exists in Genode Virtio FB driver
has one major benefit. It allows Qemu window to be dynamically resized at
runtime. The driver will treat this as resolution change and act accordingly.
Ramfb driver can currently only use the hardcoded 1024x768 screen size. Changing
screen resolution might not sound like a big deal, but it is rather useful to
run Genode on Qemu in full screen mode.
This filter bridges the gap between a touchscreen driver, which
generates raw touch events and traditional GUI applications that expect
a pointer (absolute motion, press/release of the left mouse button).
Fixes#4332
This patch changes the 'Allocator' interface to the use of 'Attempt'
return values instead of using exceptions for propagating errors.
To largely uphold compatibility with components using the original
exception-based interface - in particluar use cases where an 'Allocator'
is passed to the 'new' operator - the traditional 'alloc' is still
supported. But it existes merely as a wrapper around the new
'try_alloc'.
Issue #4324
Since the top-level node of the output ROM is always generated by the
rom_filter, there is no way to pass-through the content of an input ROM
without wrapping in an addition XML node.
genodelabs/genode#4326
This patch makes the test less dependent on the rate of state updates by
calculating the upgraded quota from the values found in the state report
instead of simply increasing the '_ram_quota' for each incoming report.
This patch replaces the 'Ram_allocator::alloc' RPC function by a
'try_alloc' function, which reflects errors as 'Attempt' return value
instead of an exception.
Issue #4322
Issue #3612
Accidentally, the size of IOMEM dataspace got accounted within the
implementation of the platform driver for ARM. Instead we should
only account a bit for the metadata and paging of the I/O memory.
Fix#4307
The custom ack avail handler is required for zero-copy nic drivers (e.g.
the zynq nic driver), which must release the corresponding DMA buffers.
Fixesgenodelabs/genode#4277
This component can service Qemu VirtIO mouse, keyboard and tablet
devices. The implementation is based on VirtIO 1.1 device spec. Its
described in section 5.8 "Input Device".
Issue #4282
This patch extends the notion of having only one uniquely hovered client
in the presence of held keys.
If motion occurs once a key is pressed (e.g., while dragging), the
receiver of the key sequence observes the motion events. In this case,
we have to submit an artificial leave event to the originally hovered
client so that no more than one client observes itself as being hovered
at the same time. Once the key sequence is finished, the hovering is
updated again, eventually presenting a motion event to the originally
hovered client and a leave event to the receiver of the key sequence.
Issue #4176
The new 'Env::try_session' method mirrors the existing 'Env::session'
without implicitly handling exceptions of the types 'Out_of_ram',
'Out_of_caps', 'Insufficient_ram_quota', and 'Insufficient_cap_quota'.
It enables runtime environments like init to reflect those exceptions to
their children instead of paying the costs of implicit session-quota
upgrades out of the own pocket.
By changing the 'Parent_service' to use 'try_session', this patch fixes
a resource-exhaustion problem of init in Sculpt OS that occurred when
the GPU multiplexer created a large batch of IO_MEM sessions, with each
session requiring a second attempt with the session quota upgraded by
4 KiB.
Issue #3767
'Out_of_ram' was so far the only exception a client had to deal with
during buffer managment. Allocating memory, however, does not only
consume RAM quota but CAP quota as well.
This commit tries to mitigate that shortcoming by reflecting the
'Out_of_caps' state back to the client. Furthermore it allows for
resource accounting on certain client allocations, e.g. buffers.
Fixes#4284.
The platform driver uses a 'Constrained_ram_allocator' to allocate
meta-data on behave of a client. It uses the PD session as
'Ram_allocator' back end that in return is implemented via the
'Expanding_pd_session_client'.
Whenever the PD client itselft comes into resource shortage it will
ask its parent unconditionally. However, depending on the integration,
such a request may be left unanswered.
This commit introduces a check to prevent that situation from
occurring. In case the platform driver notices the resource shortage
it will reflect that back to the client.
Issue #4284.
ROM clients have to request an initial update of dynamic ROMs explicitly
and should not depend on artificial signals from the ROM session on
signal-handler registration.
Issue #4274
The sequence app should immediately stop the child when it called
parent().exit(). Otherwise, the child will continue execution which
causes a race condition: The child's ld.lib.so will eventually destruct
an Attached_rom_dataspace for the config rom. If sequence destructed the
corresponding service first, we will get an Ipc_error.
genodelabs/genode#4267
This patch introduces a C API to be used by input drivers to generate
Genode events. The initial version is limited to multitouch events only.
Fixes#4273
The former implementation did not internally track ROM changes notified
vs. delivered to the client. We adapt the versioning implementation
implemented in dynamic_rom_session.h and enable explicit notification of
the current version.
The feature is used by the clipboard to notify permitted readers of the
clipboard ROM service on focus change via the newly created private
Rom::Module::_notify_permitted_readers() function.
Fixes#4274
The various mapping methods are modelled after the requirements of
the Intel GPUs or rather the Mesa driver back end.
With upcoming support for other driver back ends, we need to
sequeeze their requirements in as well. For now hijack 'map_buffer'
to provide for specifying the kind of attributes the client needs.
For now all buffers mapped in the GGTT for Intel GPUs are treated
as RW.
Issue #4265.
This call allows for checking if the given execution buffer has been
completed and complements the completion signal. Initially the GPU
multiplexer always sent such a signal when the currently scheduled
execution buffer has been completed. During enablement of the 'iris'
driver it became necessary to properly check of sequence number.
In case of the Intel GPU multiplexer the sequence numbers are
continous, which prompted the greater-than-or-equal check in the
DRM back end. By hidding this implementation detail behind the
interface, GPU drivers are free to deal with sequence numbers any
way they like and allows for polling in the client, where the
completion signal is now more of a progress signal.
Issue #4265.
The current info implementation (as RPC) is limited in a few ways:
* The amount of data that may be transferred is constrained by the
underlying base platform
* Most information never changes during run time but is copied
nonetheless
* The information differs depending on the used GPU device and
in its current implementation only contains Intel GPU specific
details
With this commit the 'info' RPC call is replaced with the
'info_dataspace' call that transfers the capability for the dataspace
containing the information only. This is complemented by a client
local 'attached_info' call that allows for getting typed access to
the information. The layout of the information is moved to its own
and GPU-specific header file, e.g., 'gpu/info_intel.h'
Issue #4265.
Rather than using the dataspace capability directly, let the client
choose its own local identifier that is linked to the underlying
capability.
Fixes#4265.
Right now the warning about failure to forward packet from driver to
uplink RX connection reads:
"exception while trying to forward packet from driverto Uplink
connection TX"
Add missing space between "driver" and "to".
Issue #4264
32KB is a rather small value. The driver can cope with it now, but
it does not perform as well as it should. This visible especially
in scenarions like nic_router_flood where we still often hit
synchronous wait path. Bump the size to 256kB.
Issue #4264
The problem can be seen when running nic_router_flood scenarion on arm
qemu_virt boards. With the amount of data this scenario tries to send
the driver quickly complains it has failed to push data into TX VirtIO
queue. After this warning message is printed nothing really happens and
after a while the test scenario fails.
The fact that we can't write all available data to the device is not
unexpected. VirtIO queue size is slected at initialization time and we
don't change it during driver lifetime. It can be tweaked via driver
config, but this does not change the fact that we'll always be able to
produce more data packets than we have free space in the VirtIO queue.
IMO the expected behavior of the driver in such case should be to:
1. Notify the device there is data to process.
2. Wait for the device to process at least part of it.
3. Retry sending queued packets.
One could expect returning Transmit_result::RETRY from _drv_transmit_pkt
would produce such result. Unfortunately it seems that Uplink_client_base
treats RETRY return value as indication of link being down. It'll retry
sending the packet only after the device notifies it the link is once
again up. This is the reason why nothing happens when running
nic_router_flood on top of virtio_nic driver. The link never goes down
in this case so once we fill the TX VirtIO queue and tell the base class
to retry the send, we'll be stuck waiting for link up change event
which will never arrive.
To fix this problem, when sending a packet to the device fails, do a
synchrnonus TX VirtIO queue flush (tell device there is data to process
and wait until its done with it).
With this fix in place nic_router_flood test scenario passes on both arm
qemu_virt boards.
Issue #4264
This commit contains features and buf fixes:
* Catch errors during resource allocation
* Because Mesa tries to allocate fence (hardware) registers for each
batch buffer execution, do not allocate new fences for buffer objects
that are already fenced
* Add support for global hardware status page. Each context additionally
has a per-process hardware status page, which we used to set the
global hardware status page during Vgpu switch. This was obviously
wrong. There is only one global hardware status page (set once during
initialization) and a distinct per-process page for contexts.
* Write the sequence number of the currently executing batch buffer to
dword 52 of the per-process hardware status page. We use the pipe line
command with QW_WRITE (quad word write), GLOBAL_GTT_IVB disabled
(address space is per-process address space), and STORE_DATA_INDEX
enabled (write goes to offset of hardware status page). This command
used to write to the scratch page. But Linux now uses the first
reserved word of the per-process hardware status page.
* Add Gen9+ WaEnableGapsTsvCreditFix workaround. This sets the "GAPS TSV
Credit fix Enable" bit of the Arbiter control register (GARBCNTLREG)
as described by the documentation this bit should be set by the BIOS
but is not on most Gen9/9.5 platforms. Not setting this bit leads to
random GPU hangs.
* Increase the context size from 20 to 22 pages for Gen9. On Gen8 the
hardware context is 20 pages (1 hardware status page + 19 ring context
register pages). On Gen9 the size of the ring context registers has
increased by two pages to 21 pages or 81.3125 KBytes as the IGD
documentation states.
* The logical ring size in the ring buffer control of the execlist
context has to be programmed with number of pages - 1. So 0 is 1 page.
We programmed the actual number of pages before, leading to ring
buffer execution of NOOPs if page behind our ring buffer was empty or
GPU hangs if there was data on the page.
issue #4260
Increased number of trace subjects since the test sporadically fails on
some platforms.
Also added a sanity check to print an error message in case we run into
the same issue again.
Fixesgenodelabs/genode#4261
The NIC router parses, stores and forwards DNS domain names from DHCP replies.
Yet the routers DHCP client used to not request DNS domain-name information on
DHCP requests. This caused DHCP servers to skip this information on their
replies although it was available. This commit fixes the issue by adding the
DNS domain name code to the request parameter list of requests from the routers
DHCP client.
The 'black_hole' component provides dummy implementations of common
session interfaces.
At this time, only the 'Audio_out' session is provided if enabled
in the configuration of the component:
<config>
<audio_out/>
</config>
Issue #3653
