[Intel-gfx] [RFC 0/2] strace/drm: Add i915 ioctls to strace
patrik.jakobsson at linux.intel.com
Mon May 11 13:54:24 UTC 2015
On Mon, May 11, 2015 at 12:50:36PM +0200, Gabriel Laskar wrote:
> On Wed, 6 May 2015 16:48:01 +0200
> Patrik Jakobsson <patrik.jakobsson at linux.intel.com> wrote:
> > This patch set aims to make strace more useful when tracing i915 ioctls.
> > The ioctl type is first checked for being drm and then the driver
> > backing the opened device is identified by looking at sysfs. Other
> > drivers than i915 can easily be added.
> > Only a subset of the i915 ioctls are included. I will extend this patch
> > set if the approach looks ok. The generic drm ioctls are also missing.
> > Give it a spin with:
> > strace -e trace=ioctl -p `pidof X`
> > Patrik Jakobsson (2):
> > strace/drm: Print extended info for drm and i915 ioctls
> > strace/drm: Print args for most common i915 ioctls
> > Makefile.am | 2 +
> > defs.h | 2 +
> > drm.c | 104 +++++++++++++++++
> > drm_i915.c | 278 +++++++++++++++++++++++++++++++++++++++++++++
> > ioctl.c | 5 +
> > xlat/drm_i915_getparams.in | 28 +++++
> > xlat/drm_i915_ioctls.in | 51 +++++++++
> > xlat/drm_i915_setparams.in | 4 +
> > 8 files changed, 474 insertions(+)
> > create mode 100644 drm.c
> > create mode 100644 drm_i915.c
> > create mode 100644 xlat/drm_i915_getparams.in
> > create mode 100644 xlat/drm_i915_ioctls.in
> > create mode 100644 xlat/drm_i915_setparams.in
> This is a great start! We need this kind of decoding. Do you plan to
> add also the generic drm ioctl decoding?
Thanks for the review. Yes, my plan is to add generic drm ioctls as well.
> Some issues though:
> * The way you avoid the ioctl request decoding is quite hard to follow,
> but it seems that you don't have much of a choice, except that in
> drm_ioctl(), the code from SYS_FUNC(ioctl) is duplicated. It seems it
> needs some work here, to allow a simpler code path. Maybe this would
> be clearer if the decoding/drm_get_driver_name, etc… was in
> ioctl_decode_command_number(). Also, with the actual code, if you are
> on i915 with an invalid ioctl number, it will be printed as
> "I915_IOCTL_???" and not "_IOC(...)" (see below for an example.) This
> will also add an inconsistent result depending whether /sys is
> mounted or not.
Yes, moving it to ioctl_decode_command_number() makes sense. I'll do that.
And I'll make the output consistent and skip the I915_IOCTL_???. It comes with
the drawback of possibly duplicated entries when doing the lookup even though we
know we're talking to i915, but it is still nicer than _???.
> * This does not compile on my system (archlinux), because drm.h lives
> in libdrm/drm.h and not in drm/drm.h, I know it is an rfc, but this
> needs to use pkg-config in order to know where libdrm headers are.
In theory libdrm is not needed since the headers are available in uapi, so I
tried to avoid adding an additional dependency. But since distros do not
guarantee the existance of <drm/drm.h> it might be better to use libdrm. I'll
look into that.
> #include <fcntl.h>
> #include <sys/ioctl.h>
> #include <unistd.h>
> #include <drm.h>
> #include <i915_drm.h>
> int main()
> int fd = open("/dev/dri/card0", O_RDWR);
> ioctl(fd, DRM_IOW(DRM_COMMAND_BASE + DRM_I915_FLUSH, int), 0);
> return 0;
> $ CFLAGS=-I/usr/include/libdrm make i915-ioctls
> cc -I/usr/include/libdrm i915-ioctls.c -o i915-ioctls
> $ sudo strace -e ioctl ./i915-ioctls
> ioctl(3, _IOC(_IOC_WRITE, 0x64, 0x41, 0x04), 0) = 0
> +++ exited with 0 +++
> $ sudo ~/source/strace/strace -e ioctl ./i915-ioctls
> ioctl(3, 0x40046441 /* I915_IOCTL_??? */, 0) = 0
> +++ exited with 0 +++
> Gabriel Laskar
More information about the Strace-devel