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Bug#1033368: marked as done (x265: nasm: use i386-baseline compatible NOP alignment)



Your message dated Sat, 25 Mar 2023 21:18:18 +0100
with message-id <ZB9XCl5pBDXi9/8u@ramacher.at>
and subject line Re: Bug#1033368: nasm: use i386-baseline compatible NOP alignment
has caused the Debian Bug report #1033368,
regarding x265: nasm: use i386-baseline compatible NOP alignment
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

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-- 
1033368: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1033368
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message ---
Source: x265
Version: 3.5-2
Severity: wishlist

Dear Maintainer,

The use of nasm 'ALIGNMODE p6'[1] in upstream's x265 source results in the nasm
assembler emitting multi-byte no-op (NOPL) instructions that are not compatible
with all systems within Debian's i386 baseline (for example: Geode LX does not
support those opcodes).

It looks like this originates from within an upstream change in Y2017.

By adjusting to 'ALIGNMODE k8' (the previous setting upstream), compatibility
with those systems could be restored (multi-byte NOPs are no longer emitted).
I'll offer a merge request on Salsa with the suggested change.

Thanks,
James

(for context: this bug was discovered while researching multi-byte NOP opcodes
as part of #1005863)

[1] - https://www.nasm.us/xdoc/2.16.01/html/nasmdoc6.html#section-6.2

[2] - https://sources.debian.org/src/libass/1%3A0.17.1-1/libass/x86/x86inc.asm/#L904

--- End Message ---
--- Begin Message ---
On 2023-03-23 18:45:54 +0000, James Addison wrote:
> Source: x265
> Version: 3.5-2
> Severity: wishlist
> 
> Dear Maintainer,
> 
> The use of nasm 'ALIGNMODE p6'[1] in upstream's x265 source results in the nasm
> assembler emitting multi-byte no-op (NOPL) instructions that are not compatible
> with all systems within Debian's i386 baseline (for example: Geode LX does not
> support those opcodes).

This is only used in an SSE2-only code path which is not supported by
Geode anyway. This shouldn't be an issue on Geode.

Cheers

> 
> It looks like this originates from within an upstream change in Y2017.
> 
> By adjusting to 'ALIGNMODE k8' (the previous setting upstream), compatibility
> with those systems could be restored (multi-byte NOPs are no longer emitted).
> I'll offer a merge request on Salsa with the suggested change.
> 
> Thanks,
> James
> 
> (for context: this bug was discovered while researching multi-byte NOP opcodes
> as part of #1005863)
> 
> [1] - https://www.nasm.us/xdoc/2.16.01/html/nasmdoc6.html#section-6.2
> 
> [2] - https://sources.debian.org/src/libass/1%3A0.17.1-1/libass/x86/x86inc.asm/#L904
> 

-- 
Sebastian Ramacher

--- End Message ---

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