Re: [FFmpeg-devel] [PATCH] fate.sh: Allow overriding what targets to make for running the tests

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH] fate.sh: Allow overriding what targets to make for running the tests
Date: Tue, 28 Nov 2023 15:21:55 +0100
Message-ID: <20231128142155.GN3543730@pb2> (raw)
In-Reply-To: <0F76AE61-2CCF-4397-BA9C-1C74AAD8BFEE@remlab.net>

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On Tue, Nov 28, 2023 at 09:27:08AM +0200, Rémi Denis-Courmont wrote:
> 
> 
> Le 28 novembre 2023 01:22:14 GMT+02:00, Michael Niedermayer <michael@niedermayer.cc> a écrit :
> >On Mon, Nov 27, 2023 at 05:46:40PM +0200, Rémi Denis-Courmont wrote:
> >[...]
> >> Also FWIW, RV broke due to misaligned accesses and illegal vector types that
> >> QEMU tolerated. That is rather an argument against QEMU than against this MR 
> >> but still.
> >
> >has someone reported this to qemu ?
> >(seems like a bug)
> 
> It's not a bug. The specification leaves those cases *undefined*. QEMU supports them because they can, and adding sanity checks would just slow stuff down.
> 
> Also generally QEMU TCG policy seems to be maximize perf and compatibility, not formal correctness.

I think i read somewhere that recent qemu supposedly checks alignment on arm
more completely. But i couldnt quickly find a official statement about that

But either way, qemu could emit such code optionally when it is used for
testing. Which is one of the things people use qemu for.
So IMHO it would make sense for qemu to detect cases that are undefined
even if for no other reason than to emulate the hw more exactly.
If this is not done, qemu can be detected and code could refuse or
fail to run

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Modern terrorism, a quick summary: Need oil, start war with country that
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be surprised about raise of fundamantalists. Drop more bombs, kill more
people, be surprised about them taking revenge and drop even more bombs
and strip your own citizens of their rights and freedoms. to be continued

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