On Mon, Dec 12, 2016 at 1:14 AM, sourab gupta <sourab.gupta@xxxxxxxxx> wrote: > On Mon, 2016-12-05 at 03:06 -0800, Dhingra, Swati wrote: >> From: Swati Dhingra <swati.dhingra@xxxxxxxxx> >> >> Currently, we don't have a stable ABI which can be used for the purpose of >> providing output debug/loggging/crc and other such data from DRM. >> The ABI in current use (filesystems, ioctls, et al.) have their own >> constraints and are intended to output a particular type of data. >> Few cases in point: >> sysfs - stable ABI, but constrained to one textual value per file >> debugfs - unstable ABI, free-for-all >> ioctls - not as suitable to many single purpose continuous data >> dumping, we would very quickly run out ioctl space; requires more >> userspace support than "cat" >> device nodes - a real possibilty, kernel instantiation is more tricky, >> requires udev (+udev.rules) or userspace discovery of the >> dynamic major:minor (via sysfs) [mounting a registered >> filesystem is easy in comparison] >> netlink - stream based, therefore involves numerous copies. >> >> Debugfs is the lesser among the evils here, thereby we have grown used to the >> convenience and flexibility in presentation that debugfs gives us >> (including relayfs inodes) that we want some of that hierachy in stable user >> ABI form. >> >> Due to these limitations, there is a need for a new pseudo filesytem, that >> would act as a stable 'free-for-all' ABI, with the heirarchial structure and >> thus convenience of debugfs. This will be managed by drm, thus named 'drmfs'. >> DRM would register this filesystem to manage a canonical mountpoint, but this >> wouldn't limit everyone to only using that pseudofs underneath. >> >> This can serve to hold various kinds of output data from Linux DRM subsystems, >> for the files which can't truely fit anywhere else with existing ABI's but >> present so, for the lack of a better place. >> >> In this patch series, we have introduced a pseudo filesystem named as 'drmfs' >> for now. The filesystem is introduced in the first patch, and the subsequent >> patches make use of the filesystem interfaces, in drm driver, and making them >> available for use by the drm subsystem components, one of which is i915. >> We've moved the location of i915 GuC logs from debugfs to drmfs in the last >> patch. Subsequently, more such files such as pipe_crc, error states, memory >> stats, etc. can be move to this filesystem, if the idea introduced here is >> acceptable per se. The filesystem introduced is being used to house the data >> generated by i915 driver in this patch series, but will hopefully be generic >> enough to provide scope for usage by any other drm subsystem component. >> >> The patch series is being floated as RFC to gather feedback on the idea and >> infrastructure proposed here and it's suitability to address the specific >> problem statement/use case. >> >> TODO: Create documentation. Will do so in next version. >> >> v2: fix the bat failures caused due to missing config check >> >> v3: Changes made: >> - Move the location of drmfs from fs/ to drivers/gpu/drm/ (Chris) >> - Moving config checks to header (Chris,Daniel) >> >> >> Sourab Gupta (4): >> drm: Introduce drmfs pseudo filesystem interfaces >> drm: Register drmfs filesystem from drm init >> drm: Create driver specific root directory inside drmfs >> drm/i915: Creating guc log file in drmfs instead of debugfs >> >> drivers/gpu/drm/Kconfig | 9 + >> drivers/gpu/drm/Makefile | 1 + >> drivers/gpu/drm/drm_drv.c | 12 + >> drivers/gpu/drm/drmfs.c | 555 +++++++++++++++++++++++++++++ >> drivers/gpu/drm/i915/i915_guc_submission.c | 33 +- >> include/drm/drm_drv.h | 3 + >> include/drm/drmfs.h | 77 ++++ >> include/uapi/linux/magic.h | 3 + >> 8 files changed, 672 insertions(+), 21 deletions(-) >> create mode 100644 drivers/gpu/drm/drmfs.c >> create mode 100644 include/drm/drmfs.h >> >> -- >> 2.7.4 >> > > Hi dri-devel folks, > > Any feedback on the proposed drmfs infrastructure being proposed here? I haven't looked too closely, but so far we haven't run into anything that we haven't been able to support via some combination of sysfs and debugfs. Alex _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
