Re: [Xen-devel] Re: [Patch RFC] ttm: nouveau accelerated on Xen pv-ops kernel

[Michael D Labriola <mlabriol@xxxxxxxx>]

Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote on 03/16/2010 
01:21:35 PM:

> > > > And my X log ends abruptly after this line:
> > > > (II) NOUVEAU(0): Opened GPU Channel 1
> > > >
> > > > Any ideas?
> > > > 
> > > 
> > > Well, this is generally the symptom that someone is confusing mfns 
and 
> > > pfns, and therefore ends up incorrectly setting the _PAGE_IO flag in 

> > > some pte.  If you run it under strace, can you identify which 
mapping 
> > > the fault is happening in?
> > 
> > I've attached the output of 'strace -o strace-Xorg Xorg'.  Figuring 
out 
> > which mapping the fault is happening in is a little over my head, I'm 
> > afraid.  If you need different arguments to strace, let me know and 
I'll 
> > do it again.
> 
> So just to be sure, you took the 2.6.32 (xen/next or
> xen/stable-2.6.32.x), copied the include and nouveu directory from ..?
> 2.6.33? and then ran this.

I actually took a slightly more sadistic route than Arvind... ;-)  A while 
back, I backported the important stuff from the Nouveau kernel git tree 
back to v2.6.31.  Basically guessed at which commits were important, wrote 
a script to cherry pick each and every one, and spent an entire day 
reading commit logs, resolving conflicts, and figuring out which other 
non-drm commits I needed.  Sounds retarded, I know, but it was a pretty 
interesting way to get myself up to speed with the code base.  The 
resulting 2.6.31-nouveau kernel runs like a champ on all my hardware.

Then I merged that into my clone of Jeremy's xen/master which I use with 
Xen 3.4.2.

Since then, I've been periodically cherry picking all new commits off the 
nouveau tree.  Also had to rebuild Xorg 7.5 to use xorg-server 1.7.5, new 
libdrm, mesa, and xf86-video-nouveau all from their respective git trees 
as of yesterday.  (drm and xf86-video-nouveau are on their master 
branches, mesa is on the 7.8 branch)

This all works great using xen/master bare metal.  It used to work fine on 
my old GeForce2 MX based systems in Xen.  Arvind's patch made it work on 
my nice new systems in Xen, but broke it on the old ones.  Everything 
still works fine bare metal.

> Did you have to edit your xorg.conf file or
> it ran just fine? 

Well, I had to create an xorg.conf that looks like this:

Section "Device"
  Identifier "foo"
  Driver "nouveau"
EndSection

Otherwise it uses the 'nv' driver...  and I haven't stumbled onto how to 
get nouveau to automatically get used (aside from uninstalling the nv 
driver).


> Was this Fedora 13 or Fedora 12?

This is all being done on a custom 32bit Linux distro that we use for our 
tightly configuration controlled system deliveries.  It was fedora based a 
looooooooong time ago (FC5), but is completely unrecognizable now.


> Arvind explanation about the Nvidia driver pointed out that the NVidia
> driver (drm/nouvue) can operate on different channels. Where channel 1
> is the framebuffer, and the other are for well, KMS, and other
> applications.
> 
> I belive I was looking at the wrong section of the drivers (not the
> drivers/video/gpu ones)- this certainly looks to be the issues the 
> Jeremy mentioned.
> 
> Also I would suggest you load drm with the debug variable set to the 255
> to get most of what his happening. 

I'll try that.


> Based on your strace, the last call is:
> 4000)                          = 0x9324000
> write(0, "(II) NOUVEAU(0): Opened GPU chan"..., 38) = 38 
> ioctl(11, 0xc0106445, 0x930a908)        = 0 
> ioctl(11, 0x400c6444, 0xbfd2a210)       = 0 
> +++ killed by SIGKILL +++
> 
> I cannot find what 0x45 is in the upstream Linux, so you must be using a
> different nouv* driver than that. The 0x44 is:
> 
>   DRM_IOCTL_DEF(DRM_NOUVEAU_GEM_INFO, nouveau_gem_ioctl_info, DRM_AUTH),
> 
> Which looks to be pretty harmless. I presume it is the next thing (using
> the address returned) that the X driver tries to do that makes it go 
boom.

I've never used strace before... how do you map between the ioctl 
definitions and the hex addresses?


---
Michael D Labriola
Electric Boat
mlabriol@xxxxxxxx
401-848-8871 (desk)
401-848-8513 (lab)
401-316-9844 (cell)



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