Re: [Xen-devel] Nouveau on dom0

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Thu, Feb 25, 2010 at 09:01:48AM -0800, Arvind R wrote:
> On Thu, Feb 25, 2010 at 6:25 PM, Konrad Rzeszutek Wilk
> <konrad.wilk@xxxxxxxxxx> wrote:
> > On Thu, Feb 25, 2010 at 02:16:07PM +0530, Arvind R wrote:
> >> Hi all,
> >> I merged the drm-tree from 2.6.33-rc8 into jeremy's 2.6.31.6 master and
> ======= snip =======
> > is not. Would it be possible to trace down who allocates that *chan? You
> > say it is 'PRAMIN' - is that allocated via pci_alloc_* call?
> >
> > Or is the address retrieved from an ioctl call made in user-space?
> Both true, I guess.
> 
> chan is GFP_KERNEL allocated. My current understanding is that
> chan->cur, at the end of a lot of initialization, points to specific
> areas of card
> memory which forms a command ring. What gets written is 32-bits which
> encode pointers to contexts and methods already associated with that
> specific channel. Each of possibly many channels have their own independent
> Command FIFOs (RINGS) and associations.
> 
> So, there must be a mmap call somewhere to map the area to user-space
> for that problem write to work on non-Xen boots. Will try track down some more
> and post. With mmaps and PCIGARTs - it will be some hunt!


You might want to look also at the source code of the nouveu X driver.
I remember looking at the radeon one, where it made an drmScatterMap
call, saved it, and then later submitted that address via an ioctl call
to the drm_radeon driver which used it as a ring buffer. Took a bit of
hoping around to find who allocated it in the first place.

> 
> >> another testing domU without devel-packages.
> >
> > You lost me here. Don't you mean Dom0?
> >
> Let's say virtual appliances - for which one needs dom0!
Ah yes.

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