Am 23.09.21 um 15:53 schrieb Zack Rusin:
On 9/20/21 10:59 AM, Zack Rusin wrote:
On Sep 20, 2021, at 02:30, Christian König
<christian.koenig@xxxxxxx> wrote:
Am 17.09.21 um 19:53 schrieb Zack Rusin:
On some hardware, in particular in virtualized environments, the
system memory can be shared with the "hardware". In those cases
the BO's allocated through the ttm system manager might be
busy during ttm_bo_put which results in them being scheduled
for a delayed deletion.
While the patch itself is probably fine the reasoning here is a
clear NAK.
Buffers in the system domain are not GPU accessible by definition,
even in a shared environment and so *must* be idle.
I’m assuming that means they are not allowed to be ever fenced then,
yes?
Any thoughts on this? I'd love a confirmation because it would mean I
need to go and rewrite the vmwgfx_mob.c bits where we use
TTM_PL_SYSTEM memory (through vmw_bo_create_and_populate) for a page
table which is read by the host, and those bo's need to be fenced to
prevent destruction of the page tables while the memory they point to
is still used. So if those were never allowed to be fenced in the
first place we probably need to add a new memory type to hold those
page tables.
Yeah, as far as I can see that is pretty much illegal from a design
point of view.
We could probably change that rule on the TTM side, but I think that
keeping the design as it is and adding a placement in vmwgfx sounds like
the cleaner approach.
Christian.
z
