Kernel patch:
Introduce a transfer item type to express that a cap should be translated
and if this fails to map it instead.
It would be possible without this combined transfer item type however
with additional overhead. In this case Genode/NOVA would
have to map and translate all caps used as parameter in IPC. It would look
like this:
* If the map and translation succeed, the cap at the new cap index
would have to be revoked. Then the translated cap index can be used.
* If the map succeeds and the translation fails then the mapped cap index
can be used.
* It would become complicated when multiple caps are mapped and translated
and only some of the translation succeed. In such cases Genode would have
to figure out the right relation of translated/mapped and not
translated/mapped caps. It would require to make some assumption about the
order how translated/mapped caps are reported at the UTCB by the kernel.
All the points above lead to the decision to create a separate transfer item
type for that.
Genode:
Most the times the translation succeeds, mapping of caps happens either
seldom. This takes now a bit the pressure of not enough aligned receive
cap windows as described in issue #247.
The patch mainly adds adjustments to handle the
translated and mapped caps correctly especially during freeing of the
receive window (don't free translated cap indexes).
Fixes#268
The additional quota is needed because of the recent performance
optimizations of the USB/networking code, e.g., to support the
increased NIC packet-stream buffer size.
Added SKB bitmap allocator, use Nic::Packet_allocator in packet stream, use slab
allocators on top of back-end AVL allocator, split allocators in cached/uncached
for general purpose/DMA allocation, added patch to original code to distinguish
cached or uncached memory requests, take advantage of and implement TX bursts
(or SKB batching), call interrupt handlers until they return unhandled.
Make calls using IPCs IRQ safe, handle packet exhaustion, removed
'Packet_pool', tweak TCP rmem and wmem buffer sizes to show better performance
results, use 'Net::Packet_allocator, fix 'update-patch' Makefile command
Avoid the use of deprecated 'MASK' enum in CPU register 'Asid'.
Enable the use of the 'K' bit in MMU translations.
Treat any try to modify existing valid entries in section- and
pagetables when doing 'insert_translation' as error.
Beautify concerned files.
By allocating the packet-stream dataspace for block sessions as
uncached, we can use DMA to directly read and write into the client
buffer. Currently, the OMAP4 SD-card driver is using this feature.
With this patch, the driver code gets complemented with DMA support.
The support for master DMA, in turn, cleared the way for using
interrupts to wait for the completion of transfers, which largely
relieves the CPU compared to the polling PIO mode. Consequently, the new
version has a much lower CPU footprint.
In the current version, both modes of operation PIO and DMA are
functional. However, PIO mode is retained for benchmarking purposes only
and will possibly be removed to keep the driver simple. It is disabled
in the driver's 'main.cc'.
This patch replaces the jiffies thread in 'sd_card/omap4/bench' calls to
'Timer::Session::elapsed_ms()'. This way, we use wall-clock time for the
measurements. Depending on the load of the rest of the system, the
previous version used to accumulate the inaccuracy for each 'msleep'
call.
For 64-bit registers we cannot compute MASK and SHIFT values via enums
because enum values are always of type int. But we can use static member
functions instead. Furthermore, the patch fixes the type trait for
64-bit registers. (apparently, this access width was never used so far)
The enable the use of 'Attached_ram_dataspace' objects as DMA buffers,
we need to pass the 'cached' flag to the constructor. By default, the
dataspace is cached, which corresponds to the original behaviour.
