Re: [PATCH] amdgpu: resize BAR0 to the maximum available size, even if it doesn't cover VRAM

[Darren Salt <devspam@moreofthesa.me.uk>]

I demand that Christian König may or may not have written...

> Am 10.12.20 um 14:59 schrieb Darren Salt:
> > I demand that Christian König may or may not have written...
> >
[snip]
>> My current kernel has another patch, applied on top of this patch, which
>> allows ignoring the size list. As such, that BAR is currently 8GB instead
>> of the 1GB which it should be. I've not noticed any significant problems
>> as yet.

> Please grab umr, take a look at the amdgpu_vram_mm debugfs file and see if
> you can get some bytes from a buffer at the end of VRAM.

> If that doesn't return 0x0 or 0xffffffff then it is probably working 
> quite fine.

I used dd:

  # dd if=/sys/kernel/debug/dri/0/amdgpu_vram bs=1048576 count=1 skip=6127 | hexdump -C |tail
  1+0 records in
  1+0 records out
  1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.0696037 s, 15.1 MB/s
  *
  000ff800  ca 53 ca 53 ca 53 ca 53  ca 53 ca 53 ca 53 ca 53  |.S.S.S.S.S.S.S.S|
  *
  000ffa00  c6 63 c6 63 c6 63 c6 63  c6 63 c6 63 c6 63 c6 63  |.c.c.c.c.c.c.c.c|
  *
  000ffe00  ca 59 ca 59 ca 59 ca 59  ca 59 ca 59 ca 59 ca 59  |.Y.Y.Y.Y.Y.Y.Y.Y|
  *
  000fff00  9a 53 9a 53 9a 53 9a 53  9a 53 9a 53 9a 53 9a 53  |.S.S.S.S.S.S.S.S|
  *
  00100000

[snip; VBIOS BAR size limit of 1GB]
> Anyway I agree that a PCI subsystem quirk might be appropriated.

My current patch set implements an override, which is definitely useful for
testing. As for adding a quirk – I've not looked into how best to do this yet.

[snip]
>> It'll also require some patching in the PCI subsystem to expose relevant
>> functions.

> Just send that to me as a complete and clean patchset.

Done, though only to the list.

> I'm the one who added the code in the first place and I have no problem 
> arguing with Bjorn why we need that in a driver now.

That's definitely helpful! ☺
_______________________________________________
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx