Re: [PATCH 0/5] drm/vmwgfx: Support module unload and hotunplug

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On Fri, 2021-10-08 at 13:31 -0400, Zack Rusin wrote:
> This is a largely trivial set that makes vmwgfx support module reload
> and PCI hot-unplug. It also makes IGT's core_hotunplug pass instead
> of kernel oops'ing.
> 
> The one "ugly" change is the "Introduce a new placement for MOB page
> tables". It seems vmwgfx has been violating a TTM assumption that
> TTM_PL_SYSTEM buffers are never fenced for a while. Apart from a
> kernel
> oops on module unload it didn't seem to wreak too much havoc, but we
> shouldn't be abusing TTM. So to solve it we're introducing a new
> placement, which is basically system, but can deal with fenced bo's.
> 
> Cc: Christian König <christian.koenig@amd.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>

Hi, Zack,

What part of TTM doesn't allow fenced system memory currently? It was
certainly designed to allow that and vmwgfx has been relying on that
since the introduction of MOBs IIRC. Also i915 is currently relying on
that.

/Thomas