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From: Florian Weimer <fweimer@redhat.com>
To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Cc: 'GNU C Library' <libc-alpha@sourceware.org>
Subject: Re: [PATCH] AArch64: Check kernel version for SVE ifuncs
Date: Thu, 14 Mar 2024 17:52:06 +0100	[thread overview]
Message-ID: <87frwskb7t.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <PAWPR08MB8982FC73FA743CECF6E1C38C83292@PAWPR08MB8982.eurprd08.prod.outlook.com> (Wilco Dijkstra's message of "Thu, 14 Mar 2024 15:38:40 +0000")

* Wilco Dijkstra:

> Hi Florian,
>
>> I generally prefer we fix the component that has the bug.  With that
>> approach, you'd have to to use your distribution contacts to request a
>> backport.
>
> The issue is present since SVE was added in 4.18 so it affects many
> kernels.  It is unlikely to be easy to backport since it relies on
> various other changes to how syscalls and register state is dealt
> with.
>
> Originally it was thought to be OK - and it would be if you only ever
> use SVE in vectorized loops. However using a few SVE instructions
> everywhere in applications breaks that model. Plus all the security
> features have increased the overhead of kernel traps in recent
> years...

Yes, that might be the case.

Can we hold off merging is for a bit?  I want to cross-checks a few
things internally before we go with the version check as proposed if
that's possible.

Thanks,
Florian


  reply	other threads:[~2024-03-14 16:52 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-13 14:31 [PATCH] AArch64: Check kernel version for SVE ifuncs Wilco Dijkstra
2024-03-13 18:12 ` Adhemerval Zanella Netto
2024-03-13 19:25   ` Szabolcs Nagy
2024-03-13 19:55     ` Adhemerval Zanella Netto
2024-03-14  8:35       ` Szabolcs Nagy
2024-03-14 13:47         ` Adhemerval Zanella Netto
2024-03-14 14:26           ` Szabolcs Nagy
2024-03-14 14:28             ` Adhemerval Zanella Netto
2024-03-14  9:02       ` Florian Weimer
2024-03-13 18:39 ` Szabolcs Nagy
2024-03-13 19:31 ` Andrew Pinski
2024-03-13 20:44   ` Wilco Dijkstra
2024-03-14  9:06 ` Florian Weimer
2024-03-14 14:42   ` Wilco Dijkstra
2024-03-14 14:55     ` Florian Weimer
2024-03-14 15:38       ` Wilco Dijkstra
2024-03-14 16:52         ` Florian Weimer [this message]
2024-03-18 11:46           ` Florian Weimer
2024-03-18 14:22             ` Wilco Dijkstra

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