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===============================================
Release notes for the Genode OS Framework 18.08
===============================================
Genode Labs
With Genode 18.08, we enter the third episode of the story of Sculpt, which is
our endeavor to shape Genode into a general-purpose operating system. In the
first two episodes, we addressed early adopters and curious technology
enthusiasts. Our current ambition is to gradually widen the audience beyond
those groups. The release reflects this by addressing four concerns that are
crucial for general-purpose computing.
First and foremost, the system must support *current-generation hardware*.
Section [Device drivers] describes the substantial update of Genode's arsenal
of device drivers. This line of work ranges from updated 3rd-party drivers,
over architectural changes like the split of the USB subsystem into multiple
components, to experimental undertakings like running Zircon drivers of
Google's Fuchsia project as Genode components.
Second, the steady stream of new discovered CPU-level vulnerabilities call
for the timely application of *microcode updates*.
Section [New Intel Microcode update mechanism] presents a kernel-agnostic
mechanism for applying CPU-microcode updates to Genode-based systems.
Third, in order to be actually useful, the system needs to be *scalable*
towards a vast variety of *workloads*. Genode's VFS infrastructure is a
pivotal element here - it is almost like a Swiss army knife. For example,
Section [New VFS plugin for using LwIP as TCP/IP stack] presents how the VFS
enables the lwIP and Linux TCP/IP stacks to be used interchangeably for a
network application by merely tweaking the component's configuration. The VFS
ultimately enables us to host sophisticated 3rd-party software, like the new
port of Python 3 (Section [Python 3]). Also on account of workload
scalability, the release features a new caching mechanism described in
Section [Cached file-system-based ROM service].
Fourth, to overcome the perception of being a toy for geeks, Sculpt must
become *easy to use*. We are aiming higher than mere convenience though. We
ought to give the user full transparency of the system's operation at an
intuitive level of abstraction. The user should be empowered to see and
consciously control the interaction of components with one another and with
the hardware. For example, unless the user explicitly allows an application to
reach the network, the application remains completely disconnected. Founded on
capability-based security, Genode already provides the solution on the
technological level. Now, we have to make this power available to the user. To
make this possible, we need to walk off the beaten tracks of commodity user
interfaces. Section [Sculpt with Visual Composition] gives a glimpse to the
upcoming features and future.
Besides the developments driven by Sculpt's requirements, the current release
features an extended Ada language runtime, updated kernels, new
multi-processor support for our custom microkernel on x86, and the ability to
route network traffic between an arbitrary number of physical network
interfaces.
Sculpt with Visual Composition
##############################
Sculpt is our take on creating a Genode-based general-purpose operating
system. With the Year of Sculpt as our leitmotif for 2018, the current release
features the ingredients of the third evolution step advertised on the
[https://genode.org/about/road-map - road map].
With Sculpt VC (Visual Composition), we pursue the gradual transition from a
text-based user interface to a graphical user interface for most
administrative tasks while preserving the text-based interface for the full
flexibility. All packages for the current version of Sculpt are readily
available at [https://depot.genode.org/genodelabs/]. The official disk image
of Sculpt VC will be released in September.
[image sculpt_18_08]
Live runtime view
-----------------
The central element of Sculpt's envisioned graphical user interface will be an
interactive representation of the runtime state, giving the user an intuitive
picture of the relationship between components and their respective trusted
computing bases, and thereby a sense of control that is unknown from today's
commodity operating systems.
[image sculpt_runtime_view]
The runtime view is generated on the fly and updated whenever the system
undergoes a structural change. It is organized such that components with a
close semantic relationship are grouped together. By default, the most
significant relationship between any two components is highlighted by a line
connecting them. The runtime view already supports a basic form of
interaction: By clicking on a component, all relationships to other components
of the runtime become visible, and additional details about the resource usage
are presented. In the forthcoming versions, the graph will become more and
more interactive.
Within Sculpt's leitzentrale, the runtime view is now displayed by default.
However, when inspecting file systems, the runtime view is replaced by the
inspect window. Both views can toggled by clicking on the title of the
storage dialog for the inspect window, or any other dialog for the runtime
view.
Revised deployment configuration
--------------------------------
In its current incarnation, the deployment of components is directly controlled
by editing the _/config/deploy_ file of Sculpt's config file system. With
the move to a non-textual user interface, this responsibility will be handed
over to the sculpt-manager component. To make this transition possible,
we moved all manually-defined parts of the deploy configuration to so-called
"launcher" configurations that reside at _/config/launcher/_. The deploy
configuration merely controls the instantiation of components while
referring to launchers. The name of each launcher corresponds to its file name.
That said, the deploy configuration is backwards compatible. Whenever a
'<start>' node contains a 'pkg' attribute, it still works as before, not using
any launcher policy.
In the new version, the default deploy configuration contains just a list of
nodes, each referring to a launcher according to the 'name' attribute. It is
possible to explicitly refer to a differently named launcher by specifying a
'launcher' attribute. This way, one launcher can be instantiated multiple
times. A '<config>' node within a launcher - when present - overrides the one
of the pkg. In turn, a '<config>' node within a node of the deploy config
overrides any other node. Both the launcher and a '<start>' node may contain a
'<route>' node. The routing rules defined in the '<start>' node have
precedence over the ones defined by the launcher. This way, the routing of a
launcher can be parameterized at the deploy configuration. The files at
_/config/launcher/_ are monitored by the sculpt manager and therefore can be
edited on the fly. This is especially useful for editing the '<config>' node
of _/config/launcher/usb_devices_rom_ to pass USB devices to a virtual
machine.
The launchers integrated in the boot image are defined at
_gems/run/sculpt/launcher/_. Each file contains a node with a mandatory pkg
attribute. If the attribute value contains one or more '/' characters, it is
assumed to be a complete pkg path of the form '<user>/pkg/<name>/<version>'.
Otherwise it is assumed to be just the pkg name and is replaced by the current
version of the current depot user's pkg at system-integration time.
Sculpt as a hardware-probing instrument
---------------------------------------
The new 'report_dump' subsystem periodically copies the content of Sculpt's
report file system to the default file system. It thereby can be used to turn
Sculpt into a diagnostic instrument for probing the driver support on new
hardware.
First, a USB stick with a fresh Sculpt image is booted on a fully supported
machine. The user then customizes the USB stick within the running system by
expanding the USB stick's Genode partition, setting it as the default
storage location, and deploying the 'report_dump' subsystem. The last step
triggers the installation of the 'report_dump' package onto the USB stick.
Finally, the user copies the deploy configuration from the in-memory config
file system (_/config/deploy_) to the USB stick
(_/usb-<N>/config/18.08/deploy_). When booting this prepared USB stick,
this deployment configuration becomes active automatically. At this point, the
Sculpt system will copy a snapshot of the report file system to the Genode
partition of the USB stick every 10 seconds. The snapshots captured on
the USB stick can later be analyzed on another machine.
The snapshots not only contain all log messages (_/report/log_) but also the
reports generated by various components of the drivers subsystem and any other
deployed components. E.g., with 'acpica' present in the deploy configuration,
the battery state is captured as well. The report-dump subsystem nicely
showcases how the addition of a simple package allows the reshaping of Sculpt
into a handy special-purpose appliance.
Device drivers
##############
Linux device-driver environment based on kernel version 4.16.3
==============================================================
We updated our DDE Linux version from 4.4.3 to 4.16.3 to support newer
Intel wireless cards as well as Intel HD graphics devices. Since there
were changes to the Linux internal APIs, we had to adapt the Linux
emulation environment. We managed to do that in a way that still makes
it possible to keep using the old Linux version for certain drivers like the
FEC network driver and the TCP/IP stack, which will be updated in the future.
Furthermore, some drivers received additional features while updating the code
base.
Updated and enhanced Intel framebuffer driver
=============================================
The updated Intel graphics driver gained support for changing the brightness
of notebook displays. The driver's configuration features a new attribute
named 'brightness' that expects a percentage value:
! ...
! <config>
! <connector name="LVDS-11" width="1280" height="800"
! hz="60" brightness="75" enabled="true"/>
! </config>
! ...
By default the brightness is set to 75 percent. The connector status report
also includes the current brightness of supported displays for each status
update.
! <connectors>
! <connector name="LVDS-11" connected="1" brightness="75">
! <mode width="1280" height="800" hz="60"/>
! ...
! </connector>
! <connector name="HDMI-A-1" connected="false"/>
! ...
! </connectors>
Updated and reworked Intel wireless driver
==========================================
The update of the iwlwifi driver's code base brings new support for 8265 as
well as 9xxx devices. The WPA supplicant code was also updated to a recent
git version that contains critical fixes for issues like the KRACK attack.
Since the updated driver requires newer firmware images which are not as easily
accessible as the old ones, we now provide the appropriate images ourselves:
[https://github.com/cnuke/dde_linux_firmware - Firmware images for DDE Linux]
We took the update as an opportunity to rework the wifi_drv's configuration
interface. The old driver used the 'wpa_supplicant.conf' POSIX config-file
interface as configuration mechanism. Unfortunately, this implementation
detail became apparent to the user of the driver because a file-system for
storing the file needed to be configured. For this reason, we now make use of
the CTRL interface of the supplicant and implemented a Genode-specific back
end. In this context, we refined the structure of the configuration of the
driver.
The driver still reports its current state but the report is now simply called
'state' instead of 'wlan_state'. At the moment, SSIDs are provided verbatim
within the report and are not sanitized. SSIDs that contain unusual characters
like '"' and the NUL byte will lead to invalid reports. This also applies for
the 'accesspoints' report that supersedes the former 'wlan_accesspoints'
report. We will address this remaining issue in a future update.
The main configuration was moved from the common '<config>' node to a new ROM
called 'wifi_config'. In doing so, we cleanly separate the wireless
configuration from the component's internal configuration, such as libc or VFS
settings that would not be changed during the component's lifetime. The new
'wifi_config' configuration looks as follows:
!<wifi_config connected_scan_interval="30" scan_interval="5">
! <accesspoint ssid="Foobar" protection="WPA2" passphrase="allyourbase"/>
!</wifi_config>
The 'connected_scan_interval' specifies the timeout after which the driver
will request a new scan of the existing access points when connected to an
access point. This setting influences the frequency at which the driver will
make a roaming decision within the network (SSID). The 'scan_interval'
attribute specifies the timeout after which a new scan request will be
executed while still trying to find a suitable access point. In addition to
those attributes there is the 'use_11n' attribute that is evaluated once on
start-up to enable or disable 11N support within the iwlwifi module. It cannot
be toggled at run-time. Furthermore there are various verbosity attributes
like 'verbose' and 'verbose_state'. If either of those is set to yes, the
driver will print diagnostic messages to the log. The verbosity can be toggled
at run-time. It is now also possible to temporarily suspend the radio activity
of the wireless device by setting the 'rfkill' attribute to 'yes'. This will
disable all connectivity and can be toggled at runtime.
The '<accesspoint>' node replaces the previously used '<selected_network>'
node. The SSID of the preferred network is set via the 'ssid' attribute. Like
the SSID in the driver's report, its value is copied verbatim. At the
moment, there is no way to express or escape non alphanumeric characters.
The type of protection of the network is set via the 'protection' attribute.
Valid values are 'WPA' and 'WPA2'. The alphanumeric password is set via the
'passphrase' attribute. Setting a PSK directly is not supported as of now. The
configuration can contain more than one '<accesspoint>' entry. In this case
the driver will choose the network that offers the best quality from the list.
To prevent the driver from auto-connecting to a network, the 'auto_connect'
attribute can be set to 'false'. The 'bssid' attribute may be used in addition
to the 'ssid' attribute to select a specific access point within one network.
There is no backwards compatibility for the old configuration format. Users
are advised to adapt their system scenarios. As an unfortunate regression,
some 6xxx cards will not work properly. This issue is being investigated.
Decomposed USB stack
====================
The USB stack has a long history in the Genode OS framework. Back in May 2009,
the first DDE-Linux-based driver was introduced, which was the USB input
driver. It used compilation units related to the USB host controller, HID, and
input subsystems of Linux. To other Genode components, it offered the input
session interface. At that time the driver ran on 32-bit x86 machines only.
Since then the USB driver underwent manifold alterations. It was extended to
support different architectures (ARMv6, ARMv7, x86_64) and USB
host-controllers of various platforms. The support for USB endpoint devices
was extended by additional HID, storage, and network devices. Nonetheless, the
USB driver remained a monolithic component comprising different session
interfaces like block, NIC and input. Nevertheless, we always regarded the
monolithic approach as an intermediate step towards a componentized USB stack,
as can be seen in the
[https://genode.org/documentation/release-notes/9.05#USB_support - release notes of 9.05].
[image multi_component_usb_1]
The first qualitative change of the USB landscape in Genode was the
introduction of the USB session interface and its support by the
DDE-Linux-based monolithic driver with the Genode release 15.02. It enabled
the development of independent driver components for USB-connected devices.
Simultaneously, the first self-contained driver was released for the Prolific
PL2303 USB to UART adapter. More, independent, written-from-scratch drivers
followed, supporting HID and USB block devices. The icing on the cake was
support of USB sessions within VirtualBox introduced in May 2015. From that
point on, it was possible to drive dedicated USB devices within a guest
operating system.
Nevertheless, the USB host-controller driver still contained the overall
complexity of Linux' input, storage, network, and USB subsystems. This
complexity is unfortunate because it inflates the trusted computing base of
all its clients. When updating different DDE Linux based drivers to a more
recent version, we finally took the opportunity to split the monolithic USB
driver stack into several parts. By separating the USB controller driver from
the actual USB device drivers, we significantly reduce the complexity of the
USB resource multiplexing.
[image multi_component_usb_2]
USB host driver
---------------
You can find the new USB host-controller-only driver for different
platforms (arndale, panda, rpi, wandboard, x86_32, x86_64) at
_repos/dde_linux/src/drivers/usb_host_. During a transitional period,
the new driver stack will exist besides the old one. Most run scripts
still use the old variant but you can have a look at the scripts
_usb_block.run_, _usb_hid.run_, and _usb_net.run_ to get a notion of
how to combine the new building blocks.
The new driver can be configured to dynamically report all USB devices
connected to the host controller and its HUBs by adding
! <report devices="yes"/>
to its configuration node. Like with the previous driver, one can use
'product_id' and 'vendor_id', or 'bus' and 'dev' number attributes - delivered
via the report - to define policy rules in the configuration of the driver.
Thereby, different client drivers can access a dedicated device only. To ease
up the migration to the new USB host driver, it is possible to just state the
'class' number within a policy rule. A USB client-side driver then is able to
open sessions for all devices of that class, but must use the correct label to
address a unique device when opening the USB session. A possible driver
configuration for the new USB host driver looks as follows.
! ...
! <provides><service name="Usb"/></provides>
! <config>
! <report devices="yes"/>
! <policy label_prefix="usb_net_drv" vendor_id="0x0b95" product_id="0x772a"/>
! <policy label_prefix="usb_block_drv" vendor_id="0x19d2" product_id="0x1350"/>
! <policy label_prefix="usb_hid_drv" class="0x03"/>
! </config>
! ...
The new host driver does not need to be configured with respect to the kind of
host controller used, e.g., OHCI, EHCI, XHCI. By providing the appropriate
device-hardware resources to the driver, it automatically detects what kind of
controller should be driven.
USB HID driver
--------------
The new self-contained USB HID driver is platform independent, as it solely
depends on the USB-session interface. It comprises drivers for several kinds
of HID devices. One can either enable support for all kinds of HID devices by
one driver instance for compatibility reasons, or use one dedicated driver
instance per HID device. To support all HID devices provided by the USB host
driver, the HID driver can subscribe to a report of the host driver. When
configuring the HID driver, like in the following snippet, it will track
changes of a ROM called 'report', and open a USB session to all HID devices
listed in the report.
! ...
! <config use_report="yes"/>
! ...
All options for tracking the state of keyboard LEDs like 'capslock', and the
configuration values to support multi-touch devices are still supported and
equal to the former monolithic driver.
USB network driver
------------------
The self-contained USB network driver is called 'usb_net_drv' and resides
at _repos/dde_linux/src/drivers_. It supports different chipsets, but
in contrast to the HID driver supports exactly one device per driver
instance. If you need support for more than one USB connected network card,
additional drivers must be instantiated. Like in the old monolithic driver, it
is advised to state a MAC for those platforms where it is not possible to read
one from an EEPROM, otherwise a hard-coded one is used.
USB devices with timing constraints
===================================
Devices like USB headsets, webcams, or sound cards require the assertion of a
guaranteed bandwidth from the USB host controller in order to function
correctly. USB achieves this through so-called isochronous endpoints, which
guarantee the desired bandwidth but do not assert the correctness of the data
delivered.
Because Genode's USB-session interface lacked support for this kind of
devices, we extended the interface and added support for isochronous endpoints
in our host controller drivers. Additionally, we adapted our Qemu-XHCI device
model to also handle isochronous requests seamlessly. With these extensions in
place, it becomes possible to directly access, for example a headset, from a
guest operating system within VirtualBox (e.g., Linux, Windows).
We consider this feature as preliminary as the current implementation limits
the support of isochronous endpoints to one IN and one OUT endpoint per USB
device.
Updated iPXE-based NIC driver
=============================
Since Genode 18.05, we extended our support of Intel Ethernet NICs by another
I219-LM variant and I218V. We also introduced I210 support including upstream
fixes for boot-time MAC address configuration.
Experimental runtime for Zircon-based drivers
=============================================
The new dde_zircon repository provides a device-driver environment for the
Zircon microkernel, which is the kernel of Google's Fuchsia OS. It consists of
the 'zircon.lib.so' shared library, which implements an adaption layer between
Zircon and Genode, and the 'zx_pc_ps2' driver that serves as a
proof-of-concept. Thanks to Johannes Kliemann for contributing this line of
work!
Improved PS/2 device compatibility
==================================
Once again we invested time into our PS/2-driver implementation due to
compatibility issues with keyboards, touchpads, and trackpoints in recent
notebooks. As a result, input devices of current Lenovo X and T notebooks as
well as the Dell Latitude 6430u work solid now.
Base framework and OS-level infrastructure
##########################################
Streamlined ELF-binary loading
==============================
In scenarios like Sculpt's runtime subsystem, a parent component may create a
subsystem out of ELF binaries provided by one of its children. However, since
the parent has to access the ELF binary in order to load it, the parent has to
interact with the child service. It thereby becomes dependent on the
liveliness of this particular child. This is unfortunate because the parent
does not need to trust any of its children otherwise. To dissolve this
unwelcome circular trust relationship, we simplified Genode's ELF loading
procedure such that the parent never has to deal with the ELF binaries
directly. Instead, the parent unconditionally loads the dynamic linker only,
which is obtained from its trusted parent. The dynamic linker - running in the
context of the new component - obtains the ELF binary as a regular ROM session
provided by a sibling component. If this sibling misbehaves for any reason,
the parent remains unaffected. To achieve this level of independence, we had
to drop the handling of statically-linked executables as first-class citizens.
In order to distinguish static from dynamic binaries, the parent needed to
look into the binary after all.
Statically linked binaries and hybrid Linux/Genode (lx_hybrid) binaries can
still be started by relabeling the ROM-session route of "ld.lib.so" to the
binary name, so as to pretend that the binary is the dynamic linker. This can
be achieved via init's label rewriting mechanism:
! <route>
! <service name="ROM" unscoped_label="ld.lib.so">
! <parent label="test-platform"/> </service>
! </route>
However, as this is quite cryptic and would need to be applied for all
lx_hybrid components, we added a shortcut to init's configuration. One can
simply add the 'ld="no"' attribute to the <start> node of the corresponding
component:
! <start name="test-platform" ld="no"/>
NIC-router support for multiple uplinks
=======================================
A comprehensive concept for the configuration of uplinks
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The main purpose of the NIC router is to mediate between an arbitrary number
of NIC sessions according to user policies for the OSI layers 3 and 4. Once a
NIC session is established and integrated into this mediation algorithm, the
fact whether the NIC router is client or server of the session becomes reduced
to subtleties that are transparent to the user. Though, when establishing the
session, there exist some differences that must be reflected by the NIC
router's configuration interface. As NIC session server, the router simply
accepts all incoming session requests, given they transfer sufficient
resources. We refer to these sessions as "downlinks". As NIC session client,
on the other hand, the router is supposed to request the desired sessions -
called "uplinks" - by itself and therefore has also to determine their session
arguments in some way.
The original version of the NIC router used a simplified model that was based
on the assumption that there is either none or only one uplink. The existence
of the one possible uplink was bound to the presence of a special domain named
"uplink" in the configuration, thereby obviating the need for uplink-specific
means of configuration.
This model has now been broken up to make room for a more potent and elegant
solution. We introduced the new '<uplink>' node for uplinks as an equivalent
to the '<policy>' node for downlinks. Like the '<policy>' node, the '<uplink>'
node assigns the corresponding NIC session to a specific domain. But unlike
the '<policy>' node, each '<uplink>' node represents exactly one uplink or NIC
session client whose lifetime and session arguments it defines. Here is a
short configuration example demonstrating the usage of the new node:
! <config>
! <policy label_prefix="virtualbox" domain="default">
! <policy label_prefix="arora" domain="wifi_domain">
!
! <uplink domain="default" />
! <uplink label="wired_1" domain="wired_bridge" />
! <uplink label="wired_2" domain="wired_bridge" />
! <uplink label="wifi" domain="wifi_domain" />
! ...
!
! <domain name="wired_bridge"> ... </domain>
! <domain name="default"> ... </domain>
! </config>
As can be observed, multiple '<uplink>' nodes are supported. The 'label'
attribute represents the label of the corresponding NIC session client. This
attribute can be omitted, which results in an empty string as label. But keep
in mind that each uplink label must be unique. The label can be used to route
different uplink sessions to different NIC servers. Assuming that the above
NIC router instance is a child of an init component, its configuration can be
accompanied by init's routing configuration as follows:
! <route>
! <service name="Nic" label="wifi"> <child name="wifi_drv"/> </service>
! <service name="Nic" label="wired_1"> <child name="nic_drv_1"/> </service>
! <service name="Nic" label="wired_2"> <child name="nic_drv_2"/> </service>
! <service name="Nic"> <parent/> </service>
! </route>
[image multiple_nic_uplinks]
The 'domain' attribute of the '<uplink>' node defines to which domain the
corresponding uplink tries to assign itself. As you can see in the example,
there is no problem with assigning multiple uplinks to the same domain or even
uplinks together with downlinks. Independent of whether they are uplinks or
downlinks, NIC sessions that share the same domain can communicate with each
other as if they were connected through a repeating hub and without any
restriction applied by the router.
Similar to downlinks, uplinks are not required to stay connected to a certain
domain during their lifetime. They can be safely moved from one domain to
another without closing the corresponding NIC session. This is achieved by
reconfiguring the respective 'domain' attribute. An uplink can even exist
without a domain at all, like the 'wifi' uplink in the example above. In this
case, all packets from the uplink are ignored by the NIC router but the
session still remains open. Finally, an uplink and its NIC session client can
be terminated by removing the corresponding '<uplink>' node from the NIC
router configuration.
ICMP echo server
~~~~~~~~~~~~~~~~
The NIC router can now act as ICMP echo server. This functionality can be
configured as shown in the following two configuration snippets:
! <config>
! <domain name="one"> ... </domain>
! <domain name="two" icmp_echo_server="no" > ... </domain>
! </config>
! <config icmp_echo_server="no">
! <domain name="three"> ... </domain>
! <domain name="four" icmp_echo_server="yes"> ... </domain>
! </config>
By default, the ICMP echo server is enabled. So, in the example above, it is
enabled for all NIC sessions assigned to domain "one" and "four". This implies
that the router will answer ICMP echo requests from sessions that target the
IP address of the corresponding domain. For the domains "two" and "three", the
ICMP echo server is disabled, meaning, that they will drop the above mentioned
requests at their NIC sessions.
New verbosity class "packet drop"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As the NIC router is being deployed in a growing number of real-live scenarios
(e.g., Sculpt OS) the ability to list dropped packets proved to be helpful
for localizing causes of complicated networking problems. But this type of
log message came along with all the other output of the routers 'verbose'
flag. Thus, we moved them to a dedicated verbosity class, which is controlled
through the new 'verbose_packet_drop' flag as illustrated by the following two
configuration snippets:
! <config>
! <domain name="one"> ... </domain>
! <domain name="two" verbose_packet_drop="yes" > ... </domain>
! </config>
! <config verbose_packet_drop="yes">
! <domain name="three"> ... </domain>
! <domain name="four" verbose_packet_drop="no"> ... </domain>
! </config>
This feature is disabled by default. So domain "one" and "four" won't log
dropped packets whereas domain "two" and "three" will. A dropped packet
message is accompanied by the rationale that led to the decision.
New VFS plugin for using LwIP as TCP/IP stack
=============================================
[image socket_fs]
The architecture and philosophy of Genode mandates that network protocol
stacks be moved up and away from the kernel whenever practical. Eliminating
the TCP/IP stack from the TCB of non-networked components has obvious
benefits, but poses a challenge for isolating or sharing IP stacks otherwise.
In
[https://genode.org/documentation/release-notes/17.02#Enhanced_VFS_infrastructure - version 17.02],
we introduced a BSD-sockets API layer to the POSIX C runtime that uses the
local virtual-file-system layer to access an abstract TCP/IP stack via control
files. A stack may be instantiated locally or shared via the File_system
service. The first stack plugin for the VFS layer was a port of the Linux IP
stack, referred to as LxIP.
Ported in the
[https://genode.org/documentation/release-notes/9.11#Light-weight_IP_stack__lwIP_ - 9.11 release],
LwIP is a lightweight alternative to LxIP. It features a low-level
asynchronous interface as well as an optional implementation of the
BSD-sockets API. In this release, we updated LwIP to the latest version,
reconfigured it for asynchronous mode only, and use its low-level API in the
new LwIP VFS plugin. This plugin retains the modest resource usage of the LwIP
library with performance that is competitive with LxIP.
The previous LwIP port has been renamed to 'lwip_legacy' and is scheduled for
removal. Developers and integrators are encouraged to transition from the old
'libc_lwip' libraries to the new VFS plugin by simply removing the legacy
libraries from components and updating configurations to load and configure
the plugin at start time.
Dynamic capability-quota balancing
==================================
Since
[https://genode.org/documentation/release-notes/17.05#Dynamic_resource_management_and_service_forwarding_via_init - version 17.05],
the init component supports the dynamic adjustment of RAM quota values. But
this mechanism remained unavailable for capability quotas. This became a
limitation in use cases like Sculpt's RAM file system where an upper bound of
needed capabilities is hard to define. For this reason, init has gained the
ability to adjust capability quotas of its children according to dynamic
configuration changes.
Simplified DNS handling of libc-using components
================================================
We overhauled the way the libc acquires DNS server information. Instead of
simply accessing the commonly used _/etc/resolv.conf_ file it now inspects the
file given by the 'nameserver_file' attribute to retrieve the DNS name server
address. It defaults to '/socket/nameserver' which is the common location when
using the lxip or lwip VFS plugin. As a constraint the libc will read the
first line and expects the verbatim name-server address.
Cached file-system-based ROM service
====================================
The fs_rom server has long been part of the foundation of dynamic Genode
systems, both for serving configuration and loading component binaries and
libraries. For the server to dynamically update ROM dataspaces as requested by
clients it must maintain independent dataspaces for each client. This is a
small price for dynamic configurations but a burden when serving more than a
few static binary images.
The new cached_fs_rom server is an alternative ROM service that deduplicates
dataspaces across client sessions as well as load and deliver sessions
out-of-order. Implementing the 'cached_fs_rom' component required an amendment
to the RM session interface to support read-only attachments in managed
dataspaces. This allows the server to allocate a managed memory region for
each session, map the dataspace with file content into the region without
write permissions, and finally hand out a dataspace capability for this region
to its client. This is the prerequisite for safely delegating shared memory
across clients.
Note that granting access to such a component would of course allow a client
to discover which files have been loaded by other components by measuring the
round-trip time for session requests, but this discovery is mitigated in
Sculpt OS by restricting components to a ROM whitelist. Under these conditions
a component may only determine if a component with a similar whitelist has
been loaded previously, but only for ROMs that have not been loaded by the
dynamic linker before measurements can be taken.
VFS plugin for importing initial content
========================================
The previous release added a long anticipated feature plugin for the VFS
layer, the Copy-On-Write plugin, or COW. This plugin transparently forwards
write operations to a read-only file to a writable file in a different
location, such as initial disk images for virtual machines. The implementation
appeared to provide these semantics without sophisticated knowledge of what
portions of a file-system had been duplicated for writing, but in practical
use the plugin suffered from a number of issues. First, the plugin was not
able to reliably detect recursion into itself, and second, chaining
asynchronous operations together proved to be more complicated than we had
planned for.
With a look on the features we were using rather than the features we
anticipated, we focused on the initial content feature of the 'ram_fs'. This
server provides a non-persistent file-system that can be populated with
content before servicing clients. To foster the goal of providing a toolkit of
orthogonal components we have been gradually merging the 'ram_fs' server, the
first file-system server, into the newer, more powerful 'vfs' server. Initial
population happened to be the last feature before parity, so we created a
special 'import' plugin for the VFS library that instantiates a temporary
internal file-system that is copied to the root of the main VFS instance. The
copy is recursive and non-destructive by default. Should the import process
need to overwrite existing files, 'overwrite="yes"' may be added to the plugin
configuration node. This plugin covers all use cases we have for the COW
plugin and turned out to be quite intuitive. Therefore, with this release, the
COW plugin is replaced by the 'import' plugin.
The plugin is quite easy to use, for example, importing a shell configuration
into a Noux instance:
! <start name="shell">
! <binary name="noux"/>
! ...
! <config>
! <start name="/bin/bash">
! <env name="HOME" value="home" />
! </start>
! <fstab>
! <tar name="coreutils.tar" />
! <fs/>
! <import overwrite="true">
! <dir name="home">
! <inline name=".bash_profile">
! PS1="\w $ "
! </inline>
! </dir>
! </import>
! </fstab>
! </config>
! </start>
To compare the use of the plugin in the VFS server:
! <start name="config_fs">
! <binary name="vfs"/>
! ...
! <config>
! <vfs>
! <ram/>
! <import>
! <dir name="managed">
! <rom name="fonts" label="fonts.config"/>
! <rom name="fb_drv" label="fb_drv.config"/>
! <rom name="wifi" label="wifi.config"/>
! <inline name="depot_query"><query/></inline>
! ...
! </dir>
! <rom name="input_filter" label="input_filter.config"/>
! <rom name="fb_drv" label="fb_drv.config"/>
! <rom name="nitpicker" label="nitpicker.config"/>
! ...
! </import>
! </vfs>
! <policy label="config_fs_rom -> " root="/" />
! <policy label="rw" root="/" writeable="yes" />
! </config>
! </start>
And the traditional 'ram_fs' content configuration:
! <start name="config_fs">
! <binary name="ram_fs"/>
! ...
! <config>
! <content>
! <dir name="managed">
! <rom name="fonts.config" as="fonts"/>
! <rom name="fb_drv.config" as="fb_drv"/>
! <rom name="wlan.config" as="wlan"/>
! <inline name="depot_query"><query/></inline>
! ...
! </dir>
! <rom name="input_filter.config" as="input_filter"/>
! <rom name="fb_drv.config" as="fb_drv"/>
! <rom name="nitpicker.config" as="nitpicker"/>
! ...
! </content>
! <policy label="config_fs_rom -> " root="/" />
! <policy label="rw" root="/" writeable="yes" />
! </config>
! </start>
Enhanced Ada language support
=============================
Genode's runtime for the Ada programming language has been extended with
exception support for C++ interfacing. Ada exceptions can now be caught in C++
and provide type and error location information when raised. Further
improvements are runtime support for 64-bit arithmetic and some minor fixes in
Gnatmake's include paths. Thanks to Johannes Kliemann for these welcome
improvements!
Enhanced Terminal compatibility
===============================
During this release cycle, a simple SSH client was added to the world
repository and we quickly noticed that our graphical terminal was unprepared
for the variety of terminal escape sequences found in the wild. The escape
sequence parser in the 'terminal' server is now able to handle or ignore the
litany of sequences that might be considered part of the ad hoc
VT100/Screen/Xterm standard. We may never be able to say that we handle them
all, but the 'terminal' server is now compatible with most robust TUI
applications.
Libraries and applications
##########################
Python 3
========
Thanks to the work of Johannes Schlatow, Python 3 has become available at the
[https://github.com/genodelabs/genode-world - Genode-world] repository. It
supersedes Genode's original Python 2 port, which is scheduled for removal now.
The Python 3 port is accompanied with the _python3.run_ script for a quick
test drive. It also features depot-archive recipes, which in principle enable
the deployment of Python 3 within Sculpt OS.
New component for querying information from a file system
=========================================================
There are situations where a security critical application needs to obtain
information stored on a file system but must not depend on the liveliness of
the file-system implementation. A prominent example is the sculpt manager of
Sculpt OS. Instead of accessing file systems directly, it uses a helper
component that performs the actual file-system access and generates a report
containing the aggregated information. Should the file system crash or become
unavailable for reasons such as the removal of a USB stick, the helper
component may get stuck but the security-critical application remains
unaffected.
The new fs_query component resides at _repos/gems/src/app/fs_query/_ and is
accompanied with the _fs_query.run_ script. The file system is configured as a
component-local VFS. The component accepts any number of '<query>' nodes
within its '<config>' node. Each '<query>' node must contain a 'path'
attribute pointing to a directory to watch. The component generates a report
labeled "listing". For each existing directory queried, the report contains a
'<dir>' node with the list of files as '<file>' nodes featuring the
corresponding 'name' as an attribute value.
A '<query>' can be equipped with a 'content="yes"' attribute. If set, the
content of the queried files is supplemented as body of the '<file>' nodes.
The reported content is limited to 4 KiB per file. If the content is valid
XML, the '<file>' node contains an attribute 'xml="yes"' indicating that the
XML information is inserted as is. Otherwise, the content is sanitized.
Updated ported 3rd-party software
=================================
User-level ACPICA
-----------------
We have updated our port of the ACPI Component Architecture (ACPICA) from
version 2016-02-12 to the most recent release version 2018-08-10. This was
motivated by recent notebooks that apparently were not supported
well by the old version. According to the ACPICA documentation, this update
mainly marks the step from ACPI specification version 6.1 to 6.2 and, as
hoped, our problems with modern laptops got fixed too.
VirtualBox
----------
We updated the VirtualBox 5 port on Genode to the latest available 5.1
version (5.1.38).
Platforms
#########
New Intel Microcode update mechanism
====================================
Applying CPU microcode patches is a common task for the UEFI/BIOS firmware
shipped by hardware vendors of PCs and/or motherboards. For various
reasons, however, machines may not receive firmware updates as often
or as quickly as they should. Based on the recent high rate of disclosures for
Spectre-related hardware bugs in CPUs, there is the desire to use microcode
updates as rapidly as they are released. To address this concern, we added
principle support for applying Intel microcode patches as part of the Genode
framework.
The first step was to add support to download the Intel microcode patches via
the Genode port mechanism.
! tool/ports/prepare_port microcode_intel
As next step, a Genode component, showcased by _repos/ports/run/microcode.run_,
can compare the current microcode patch level on Genode/NOVA with the
downloaded Intel microcode. The relevant information about the CPUs and their
microcode patch level are provided by the 'platform_info' ROM on Genode/NOVA.
If a microcode update is necessary, the Intel microcode can be applied during
the next boot. We decided to implement this functionality as a separate
chained bootloader called 'microcode' in order to not inflate each of our
supported x86 kernels with additional management code for applying microcode
patches on all CPUs. The 'microcode' bootloader expects a module called
'micro.code' which contains the specific Intel microcode from the
'microcode_intel' port for the target CPU. The relevant excerpt of a Genode
GRUB2 configuration looks like this:
! multiboot2 /boot/bender
! module2 /boot/microcode
! module2 /boot/micro.code micro.code
! module2 /boot/hypervisor hypervisor ...
! module2 /boot/image.elf.gz image.elf
The microcode update functionality has been integrated into the
_tool/run/boot_dir/nova_ support file and can be enabled by providing a
'apply_microcode' TCL procedure as showcased in _repos/ports/run/microcode.run_.
We developed the 'microcode' chained bootloader as part of the
[https://github.com/alex-ab/morbo - Morbo] project. It checks for an Intel CPU
and a valid 'micro.code' module that matches the currently running CPU.
Afterwards, the bootloader looks up all CPUs and some LAPIC information by
parsing the relevant ACPI tables. With this information, the CPUs are booted
to apply the microcode update to each processor. On CPUs with hyperthreading
enabled, it is effectual to start a single hyperthread per CPU to apply the
update. Finally, all previously started CPUs are halted and the microcode
bootloader hands over control to the next module which is typically the x86
kernel.
Multiprocessor support for our custom kernel on x86
===================================================
As announced on this year's roadmap, we extended our 'hw' kernel on x86 with
multiprocessor support. The 'bootstrap' part of the kernel now parses ACPI
tables to obtain the required CPU information and finally starts them. The
number of the running CPUs is reported by 'bootstrap' to the 'hw' kernel to
foster the x86 case, where the maximum supported number of CPUs is not
identical to the number of running CPUs. This is in contrast to our supported
ARM boards where both numbers are the same.
NOVA microhypervisor
====================
The NOVA kernel branch in use has been switched to revision r10, which is an
intermediate result of [https://cyberus-technology.de/ - Cyberus Technology]
and of [https://www.genode-labs.com/ - Genode Labs] to harmonize their
independently developed NOVA kernel branches. We hope to mutually benefit from
the evolution of NOVA over the long run by having a common NOVA trunk and
short individual branches.
Feature-wise the r10 branch contains the following changes:
* Export kernel trace messages via memory, which can be used by Genode
for debugging purposes. The feature is used in Sculpt OS
already and may be tested by _repos/os/run/log_core.run_.
* Cross-core IPC via NOVA portals can now be restricted.
* Avoid general protection fault on AMD machines where SVM is disabled by UEFI
firmware
* More robust ACPI table parsing of broken/defect ACPI tables
* Using eager FPU switching on Intel CPUs to mitigate Spectre FPU CVE
* Report CPU microcode patch level information via the hypervisor information
page
Fiasco.OC microkernel updated
=============================
In the past, we repeatedly encountered problems with kernel object destruction
when using Genode on top of the Fiasco.OC microkernel. The effect was a
non-responsive kernel and halt of the machine. Thanks to recent development of
the Fiasco.OC/L4Re community, those problems seem to be solved now. Jakub
Jermar gave us the hint to update to a more recent kernel version, which
solved the observed issues.
Now, the Genode fork of the Fiasco.OC version is based on the official Github
sources from
[https://github.com/kernkonzept/fiasco/commit/b9145d3ec4ffe3b02b3d49475ff3391905f0b51f - June 25, 2018].
The L4Re parts that are used by Genode, namely the sigma0 and bootstrap
components, are still based on the official [https://svn.l4re.org/repos/oc/l4re/ - subversion repository],
referring to revision 79.
Build system and tools
######################
Improved run tool
=================
Genode's run tool automates the workflows for building, configuring,
integrating, and executing system scenarios.
Unified precondition checks
---------------------------
We refined the run tool by removing the 'check_installed' and
'requires_installation_of' functions. They were used to determine if a certain
shell command was present on the host system and are now superseded by the
'installed_command' function. This new function also checks if a shell command
is present on the system by searching the PATH variable and additionally the
'sbin' directories that might not be part of the PATH on some Linux
distributions. If a shell command cannot be located, a warning message will be
given and the run script will be aborted.
Optional preservation of boot-directory content
-----------------------------------------------
Executing a run script on Genode yields the creation of image files (e.g.,
'image.elf', '<run-script>.img' ...). These image files are created from a
temporary directory under _<build_dir>/var/run/<run-script>/genode_, where the
Genode components required by the run script are being stored.
After image creation, it becomes difficult to determine the set of components
present in a certain image. Therefore, we added a new run option for our
RUN_OPT environment variable called '--preserve-genode-dir', which leaves the
temporary 'genode' directory intact.
! RUN_OPT += --preserve-genode-dir
This way all Genode components of an image file can be inspected with ease.
Note that this option inflates the size of the resulting boot image because
the content is contained twice, once in the 'image.elf' file and once in the
_genode/_ directory.
Configurable AMT power-on timeout
---------------------------------
Boot time may vary vastly between PCs. This is particularly troublesome when
AMT Serial-Over-LAN is the only debug option for different test machines.
Because Intel ME is quite picky at which time window AMT SOL connects, it may
just fall flat. So, we added a run option to optionally change the default AMT
boot timeout of 5 seconds like follows.
!RUN_OPT += --power-on-amt-timeout 11
On some PCs, we had to increase this option up to 26 seconds, which may
further increase with attached USB mass storage if USB boot is enabled.
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