On Wed, Feb 2, 2011 at 4:12 PM, Miklos Aubert [off-list ref] wrote:

Hello fellow RT users,

I've built a 2.6.33.7 kernel with the RT patch and the Nouveau driver
enabled, but Xorg doesn't start.

Using the _same_ configuration and removing the RT patch (vanilla
kernel from kernel.org), Xorg works.

Booting with drm.debug=1, and comparing the kernel logs, I find that
the RT kernel seems to be having trouble here :

[   31.651720] [drm:drm_ioctl], pid=1904, cmd=0x6440, nr=0x40, dev
0xe200, auth=1
[   31.651724] [drm:drm_ioctl], no function
[   31.651726] [drm:drm_ioctl], ret = ffffffea

These messages come from the drm_ioctl() function in
drivers/gpu/drm/drm_drv.c. But which ioctl are we calling here ? I
guess one can find it from the cmd=0x6440 code. Not me though, I tried
to make sense of the source code, but my C is very rusty and it's
macros and includes all the way down...

Anyway, to me this problem seems to come from the modifications that
the RT patch does on drivers/gpu/drm/nouveau/nouveau_channel.c. It
changes the definition macro from DRM_IOCTL_DEF to DRM_IOCTL_DEF_DRV,
but also removes some lines. Why ?

The removals you point at are due to the different baseline of 33.7 vs. whatever
you are comparing it to.  They dont come from RT, as you can see below:

-------------------------
patches$grep -l nouveau *
printk-convert-console_sem-to-console_mutex.patch
patches$diffstat -p0
printk-convert-console_sem-to-console_mutex.patch|grep nouveau
 b/drivers/gpu/drm/nouveau/nouveau_drv.c  |    8 +-
patches$grep DRM_IOCTL_DEF printk-convert-console_sem-to-console_mutex.patch
patches$
-------------------------

You can verify the above yourself by cloning:

git://git.kernel.org/pub/scm/linux/kernel/git/paulg/rt-patches.git

and checking out origin/v2.6.33-rt (which is content identical to 33.7-rt30).

Paul

 struct drm_ioctl_desc nouveau_ioctls[] = {
-   DRM_IOCTL_DEF(DRM_NOUVEAU_CARD_INIT, nouveau_ioctl_card_init, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GETPARAM, nouveau_ioctl_getparam, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_SETPARAM, nouveau_ioctl_setparam,
DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_CHANNEL_ALLOC, nouveau_ioctl_fifo_alloc,
DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_CHANNEL_FREE, nouveau_ioctl_fifo_free, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GROBJ_ALLOC, nouveau_ioctl_grobj_alloc, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_NOTIFIEROBJ_ALLOC,
nouveau_ioctl_notifier_alloc, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GPUOBJ_FREE, nouveau_ioctl_gpuobj_free, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GEM_NEW, nouveau_gem_ioctl_new, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GEM_PUSHBUF, nouveau_gem_ioctl_pushbuf, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GEM_PUSHBUF_CALL,
nouveau_gem_ioctl_pushbuf_call, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GEM_PIN, nouveau_gem_ioctl_pin, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GEM_UNPIN, nouveau_gem_ioctl_unpin, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GEM_CPU_PREP,
nouveau_gem_ioctl_cpu_prep, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GEM_CPU_FINI,
nouveau_gem_ioctl_cpu_fini, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GEM_INFO, nouveau_gem_ioctl_info, DRM_AUTH),
-   DRM_IOCTL_DEF(DRM_NOUVEAU_GEM_PUSHBUF_CALL2,
nouveau_gem_ioctl_pushbuf_call2, DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_GETPARAM, nouveau_ioctl_getparam, DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_SETPARAM, nouveau_ioctl_setparam,
DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_CHANNEL_ALLOC, nouveau_ioctl_fifo_alloc,
DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_CHANNEL_FREE, nouveau_ioctl_fifo_free, DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_GROBJ_ALLOC, nouveau_ioctl_grobj_alloc, DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_NOTIFIEROBJ_ALLOC,
nouveau_ioctl_notifier_alloc, DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_GPUOBJ_FREE, nouveau_ioctl_gpuobj_free, DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_GEM_NEW, nouveau_gem_ioctl_new, DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_GEM_PUSHBUF, nouveau_gem_ioctl_pushbuf, DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_GEM_CPU_PREP,
nouveau_gem_ioctl_cpu_prep, DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_GEM_CPU_FINI,
nouveau_gem_ioctl_cpu_fini, DRM_AUTH),
+   DRM_IOCTL_DEF_DRV(NOUVEAU_GEM_INFO, nouveau_gem_ioctl_info, DRM_AUTH),
 };
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