From: Christian Zigotzky <chzigotzky@xenosoft.de>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Darren Stevens <darren@stevens-zone.net>,
Andrew Donnellan <ajd@linux.ibm.com>,
npiggin@gmail.com, rmclure@linux.ibm.com,
mad skateman <madskateman@gmail.com>,
Olof Johansson <olof@lixom.net>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Trevor Dickinson <rtd2@xtra.co.nz>,
Christian Zigotzky <info@xenosoft.de>
Subject: Re: Issues with the first PowerPC updates for the kernel 6.1
Date: Sun, 30 Oct 2022 08:57:25 +0100 [thread overview]
Message-ID: <d906bcb4-e6f7-1268-b787-bd283a964b6f@xenosoft.de> (raw)
In-Reply-To: <20221029153331.GI25951@gate.crashing.org>
On 29 October 2022 at 5:33 pm, Segher Boessenkool wrote:
> On Mon, Oct 17, 2022 at 09:53:04AM +0200, Christian Zigotzky wrote:
>>> On 17. Oct 2022, at 02:43, Michael Ellerman <mpe@ellerman.id.au> wrote:
>>> Previously BIG_ENDIAN && GENERIC_CPU would use -mcpu=power5, now it uses
>>> -mcpu=power4.
>> Maybe this is the issue. We will wait and not release the RC1 for testing because it is a risk for our testers to test these new kernels because of this issue.
>>
>> It is really important do not to rewrite code, that is well worked before.
>> Bugfixing and adding some new features is ok but rewriting of good code is expensive and doesn’t make any sense.
> It was just a bugfix, and a (partial) revert.
>
> 471d7ff8b51b says it removed ISA 2.00 support (original power4, "GP").
> Support for ISA 2.01 was retained it says. That is power4+, "GQ", but
> also 970 (Apple G5). That patch actually switched to ISA 2.02 though,
> unintendedly, and code generated for ISA 2.02 will not run on systems
> like 970, in principle. It is just one uncommon instruction that is
> problematical, namely popcntb, because the kernel does not use floating
> point at all, so that is why we got away with it for so long (most code
> that does use fp will fall flat on its face in no time). It still is a
> bug fix though!
>
> PA6T is ISA 2.04, it's not clear how this (bugfix, and revert!) change
> made code not run on PA6T anymore. Smells a lot like something indirect
> (or triply indirect), a separate bug, something that was introduced in
> the last two years maybe, but I'll even bet it is something *exposed* in
> that time, a bug that has been here for longer!
>
>
> Segher
Unfortunately my FSL P5040 system is also affected.
-- Christian
next prev parent reply other threads:[~2022-10-30 7:58 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-12 6:51 Issues with the first PowerPC updates for the kernel 6.1 Christian Zigotzky
2022-10-12 7:56 ` Andrew Donnellan
2022-10-13 7:03 ` Christian Zigotzky
2022-10-13 7:28 ` Christophe Leroy
2022-10-13 9:42 ` Christian Zigotzky
2022-10-13 9:46 ` Christian Zigotzky
2022-10-14 16:11 ` Christian Zigotzky
2022-10-14 18:47 ` Olof Johansson
2022-10-17 0:17 ` Michael Ellerman
2022-10-16 16:46 ` Segher Boessenkool
2022-10-16 17:32 ` Christian Zigotzky
2022-10-17 0:42 ` Michael Ellerman
2022-10-17 7:53 ` Christian Zigotzky
2022-10-29 15:33 ` Segher Boessenkool
2022-10-30 7:57 ` Christian Zigotzky [this message]
[not found] ` <fe06590f-6db6-f5cc-72ec-e635f66f3d3b@xenosoft.de>
2022-10-29 13:52 ` Christian Zigotzky
2022-10-30 13:30 ` Christian Zigotzky
2022-11-01 16:46 ` Christian Zigotzky
2022-10-15 9:50 ` Andrew Donnellan
2022-10-15 21:05 ` Christian Zigotzky
2022-10-30 16:46 ` Issues with the first PowerPC updates for the kernel 6.1 #forregzbot Thorsten Leemhuis
2022-11-03 0:08 ` Michael Ellerman
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