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From: Darren Salt <devspam@moreofthesa.me.uk>
To: christian.koenig@amd.com
Cc: amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH] amdgpu: resize BAR0 to the maximum available size, even if it doesn't cover VRAM
Date: Fri, 11 Dec 2020 19:48:08 +0000	[thread overview]
Message-ID: <58E2C3B550%devspam@moreofthesa.me.uk> (raw)
In-Reply-To: <77805324-8fdc-8d72-f033-7d75ae04947e@gmail.com>

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

> Am 11.12.20 um 02:42 schrieb Darren Salt:
>> I demand that Christian König may or may not have written...
> [SNIP]

> Well I did wrote that :)

“did write”, surely…

>> I used dd:
>> # dd if=/sys/kernel/debug/dri/0/amdgpu_vram bs=1048576 count=1 skip=6127 | hexdump -C |tail

> That won't work. amdgpu_vram uses a MMIO register pair to access VRAM which
> works even when it isn't CPU visible.

> Thinking more about it umr would probably use this as well, so that won't
> work either.

> You could try to use dd on /dev/mem with the offset of the BAR.

Looks like that's RAM accessed by physical address, so that won't work
either. And I do see dd reporting ‘bad address’.

>> Anyway I agree that a PCI subsystem quirk might be appropriated.

> I'm going to discuss AMD internally why you have such strange values in 
> the RBAR registers.

I'm thinking probably an error by somebody at Sapphire, but we'll see…

Hopefully, that'll sort it out, at least for new cards. I doubt that mine's
the only one like this, and it seems likely that most already out there won't
be updated (shoudl there be new VBIOS releases as a reault).

Anyway, I have a quirk patch written now – untested as yet, and probably
going to be changed due to other changes before I do test it.

[snip]
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      reply	other threads:[~2020-12-11 19:49 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-10  0:57 [PATCH] amdgpu: resize BAR0 to the maximum available size, even if it doesn't cover VRAM Darren Salt
2020-12-10 10:17 ` Christian König
2020-12-10 13:59   ` Darren Salt
2020-12-10 20:41     ` Christian König
2020-12-11  1:42       ` Darren Salt
2020-12-11 16:46         ` Christian König
2020-12-11 19:48           ` Darren Salt [this message]

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