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.
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.
Increase size of block session backing store so it can handle maximum supported
packet size. Synchronize client threads during packet allocation.
Fixes#276
The block test at test/ahci is indeed not AHCI-specific. It is a generic
block read/write test for the block-session interface. But in contrast
to the original test/block, it restores the block device content (at
least when the test succeeds). Hence, we remove the original (dangerous)
block test and always use code of test/ahci.
The new SD card driver at 'os/src/drivers/sd_card/omap4' allows the use
of an SD card with the Pandaboard as block service. Currently, the
driver is using PIO, no DMA, and no IRQs. The driver can be tested using
the 'os/run/sd_card.run' script.
This patch replaces the first attempt to resolve the ambiguity of using
the size_t type that occurred when 'loader_session.h' was included
alongside libc headers. Instead of explicitly qualifying each occurrence
of the type, the new solution defines 'size_t' within the 'Loader' namespace.
Fixes#253
The compiler complained about ambigous references when compiling a
lx_hybrid program using the loader session. Here are some error
messages:
genode/os/include/loader_session/loader_session.h:72: error: reference to 'size_t' is ambiguous
/usr/lib/gcc/i486-linux-gnu/4.4.5/include/stddef.h:211: error: candidates are: typedef unsigned int size_t
genode/base/include/base/stdint.h:25: error: typedef unsigned int Genode::size_t
genode/os/include/loader_session/loader_session.h:72: error: reference to 'size_t' is ambiguous
/usr/lib/gcc/i486-linux-gnu/4.4.5/include/stddef.h:211: error: candidates are: typedef unsigned int size_t
genode/base/include/base/stdint.h:25: error: typedef unsigned int Genode::size_t
...
This commit qualifies size_t using the Genode namespace which fixes
the compilation.
This patch extends the RAM session interface with the ability to
allocate DMA buffers. The client specifies the type of RAM dataspace to
allocate via the new 'cached' argument of the 'Ram_session::alloc()'
function. By default, 'cached' is true, which correponds to the common
case and the original behavior. When setting 'cached' to 'false', core
takes the precautions needed to register the memory as uncached in the
page table of each process that has the dataspace attached.
Currently, the support for allocating DMA buffers is implemented for
Fiasco.OC only. On x86 platforms, it is generally not needed. But on
platforms with more relaxed cache coherence (such as ARM), user-level
device drivers should always use uncacheable memory for DMA transactions.
This patch implements a simple Qt-based media player which is actually a
graphical user interface for the SDL-based 'avplay' media player from
'libav'. It starts 'avplay' as a child and shows its graphical output in a
'QNitpickerViewWidget'. The widgets for controlling the player state send
the according keyboard and mouse input events to 'avplay'.
The 'qt_avplay' player supports the following configuration options:
<mediafile name="..."/>
-> name of the media file to play
<framebuffer_filter name="..." ram_quota="..."/> (may appear multiple times)
-> name of a framebuffer filter service to filter the video output
Fixes#222.
The new 'dde_linux' repository will host device drivers ported from the
Linux kernel. In contrast to the original 'linux_drivers' repository,
'dde_linux' does not contain any 3rd-party source code. To download the
Linux kernel source code and extract the drivers, execute the 'make
prepare' rule of the top-level Makefile. The initial version of the
'dde_linux' repository comes with an USB driver. The porting methodology
follows the path of the Intel GEM port. Instead of attempting to provide
a generic Linux environment that works across drivers, each driver comes
with a specially tailored DDE.
The DDE consists of Genode-specific implementations of Linux API
functions as declared in 'lx_emul.h'. Most of these functions are
dummies that must merely be provided to resolve dependencies at the
linking stage. They are called by unused code-paths.
As of now, the USB driver support UHCI, EHCI on the x86_32 platform. I
exposes USB HID devices and USB storage devices via Genode's input-session
and block-session respectively.
The USB driver is accompanied with two run scripts 'run/usb_hid.run' and
'run/usb_storage.run'.
This commit adds a terminal_log component, and a run-script which demonstrates
its usage. The terminal_log component provides the LOG service, and prints
every log-output prefixed by the session-label via a terminal-session.
This patch introduces the file-system-session interface, provides an
implementation of this interface in the form of an in-memory file
system, and enables the libc to use the new file-system facility.
The new interface resides in 'os/include/file_system_session/'. It
uses synchronous RPC calls for functions referring to directory
and meta-data handling. For transferring payload from/to files, the
packet-stream interface is used. I envision that the asynchronous design
of the packet-stream interface fits well will the block-session
interface. Compared to Unix-like file-system APIs, Genode's file-system
session interface is much simpler. In particular, it does not support
per-file permissions. On Genode, we facilitate binding policy (such as
write-permission) is sessions rather than individual file objects.
As a reference implementation of the new interface, there is the
new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse
files in memory. At the startup, 'ram_fs' is able to populate the
file-system content with directories and ROM modules as specified
in its configuration.
To enable libc-using programs to access the new file-system interface,
there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this
plugin, files stored on a native Genode file system can be accessed
using the traditional POSIX file API.
To see how the three parts described above fit together, the test
case at 'libports/run/libc_fs' can be taken as reference. It reuses
the original 'libc_ffat' test to exercise several file operations
on a RAM file-system using the libc API.
:Known limitations:
The current state should be regarded as work in progress. In particular
the error handling is not complete yet. Not all of the session functions
return the proper exceptions in the event of an error. I plan to
successively refine the interface while advancing the file-system
implementations. Also the support for truncating files and symlink
handling are not yet implemented.
Furthermore, there is much room for optimization, in particular for the
handling of directory entries. Currently, we communicate only one dir
entry at a time, which is bad when traversing large trees. However, I
decided to focus on functionality first and defer optimizations (such as
batching dir entries) to a later stage.
The current implementation does not handle file modification times at
all, which may be a severe limitation for tools that depend on this
information such as GNU make. Support for time will be added after we
have revisited Genode's timer-session interface (issue #1).
Fixes#54Fixes#171
