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Groups > linux.debian.kernel > #88514 > unrolled thread

Bug#1109776: Support for non-4kB pages in Xe driver

Started byBastian Blank <waldi@debian.org>
First post2025-07-23 18:10 +0200
Last post2025-07-23 18:50 +0200
Articles 2 — 2 participants

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  Bug#1109776: Support for non-4kB pages in Xe driver Bastian Blank <waldi@debian.org> - 2025-07-23 18:10 +0200
    Bug#1109776: Support for non-4kB pages in Xe driver Simon Richter <sjr@debian.org> - 2025-07-23 18:50 +0200

#88514 — Bug#1109776: Support for non-4kB pages in Xe driver

FromBastian Blank <waldi@debian.org>
Date2025-07-23 18:10 +0200
SubjectBug#1109776: Support for non-4kB pages in Xe driver
Message-ID<LbKcx-25R8-3@gated-at.bofh.it>
Control: tags -1 moreinfo

On Thu, Jul 24, 2025 at 12:45:39AM +0900, Simon Richter wrote:
> this is a set of backported patches to make the Xe driver in the stable
> kernel not Oops when run on a machine with a page size that isn't 4k.

I see that patches on stable@, we won't take patches that can go this
way usually.

Bastian

-- 
Not one hundred percent efficient, of course ... but nothing ever is.
		-- Kirk, "Metamorphosis", stardate 3219.8

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#88515

FromSimon Richter <sjr@debian.org>
Date2025-07-23 18:50 +0200
Message-ID<LbKPf-266W-5@gated-at.bofh.it>
In reply to#88514
Hi,

On 7/24/25 00:59, Bastian Blank wrote:

>> this is a set of backported patches to make the Xe driver in the stable
>> kernel not Oops when run on a machine with a page size that isn't 4k.

> I see that patches on stable@, we won't take patches that can go this
> way usually.

The full patchset[1] for later kernels has a bunch of extra changes, but 
the stable kernel is old enough that we can get by with a number of 
simple substitutions:
  - replace SZ_4K with PAGE_SIZE when finding an alignment palatable to 
the CPU
  - replace PAGE_SIZE with SZ_4K when describing a memory layout in GPU 
memory that uses 4k alignment regardless of host page size.

So on 4k, where PAGE_SIZE *is* SZ_4K, this does nothing, but it fixes 
the Oops on boot for 16k (aarch64, loong64) and 64k (ppc64le) users.

Since these are derived from the proper fix, you can easily see when 
they are no longer required.

    Simon

[1] 
https://lore.kernel.org/all/20250604-upstream-xe-non-4k-v2-v2-0-ce7905da7b08@aosc.io/

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