On Wed, 6 May 2015 16:48:01 +0200
Patrik Jakobsson <patrik.jakobsson@xxxxxxxxxxxxxxx> 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?
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.
* 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.
#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
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