From: Alexander Graf <agraf@suse.de>
To: "Andreas Färber" <andreas.faerber@web.de>
Cc: kennethsalerno@yahoo.com, paulus@samba.org,
qemu-devel@nongnu.org, David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [Qemu-devel] [PATCH] Fix a bug in mtsr/mtsrin emulation on ppc64
Date: Sat, 21 May 2011 11:46:12 +0200 [thread overview]
Message-ID: <CCDE4FD9-9DE0-475C-AB79-6F99E84F7FC5@suse.de> (raw)
In-Reply-To: <2C123A3E-DA94-482E-A3AD-8BC042A34BD1@web.de>
On 21.05.2011, at 11:40, Andreas Färber wrote:
> Am 20.05.2011 um 09:40 schrieb Alexander Graf:
>
>> On 20.05.2011, at 05:34, David Gibson wrote:
>>
>>> Early ppc64 CPUs include a hack to partially simulate the ppc32 segment
>>> registers, by translating writes to them into writes to the SLB. This is
>>> not used by any current Linux kernel, but it is used by the openbios used
>>> in the qemu mac99 model.
>>>
>>> Commit 81762d6dd0d430d87024f2c83e9c4dcc4329fb7d, cleaning up the SLB
>>> handling introduced a bug in this code, breaking the openbios currently in
>>> qemu. Specifically, there was an off by one error bitshuffling the
>>> register format used by mtsr into the format needed for the SLB load,
>>> causing the flag bits to end up in the wrong place. This caused the
>>> storage keys to be wrong under openbios, meaning that the translation code
>>> incorrectly thought a legitimate access was a permission violation.
>>>
>>> This patch fixes the bug, at the same time it fixes some build bug in the
>>> MMU debugging code (only exposed when DEBUG_MMU is enabled).
>>
>> Thanks, applied to ppc-next :)
>
> Hm. Don't you think we should split off the unrelated debug code fix for bisecting?
Not sure if it's worth the effort. If you were bisecting before that, you probably had DEBUG_MMU disabled anyways, because you'd otherwise get build breakages before that specific commit anyways, so the commit behaves as if it's only the SLB fix.
Alex
next prev parent reply other threads:[~2011-05-21 9:46 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-20 3:34 [Qemu-devel] [PATCH] Fix a bug in mtsr/mtsrin emulation on ppc64 David Gibson
2011-05-20 7:40 ` Alexander Graf
2011-05-20 22:37 ` Andreas Färber
2011-05-21 1:58 ` Alexander Graf
2011-05-21 9:39 ` Andreas Färber
2011-05-21 9:44 ` Alexander Graf
2011-05-21 12:16 ` Alexander Graf
2011-05-21 9:39 ` Alexander Graf
2011-05-21 9:40 ` Andreas Färber
2011-05-21 9:46 ` Alexander Graf [this message]
2011-05-21 11:13 ` David Gibson
2011-05-21 11:22 ` Alexander Graf
2011-05-21 9:46 ` Andreas Färber
-- strict thread matches above, loose matches on Subject: below --
2011-05-20 3:33 David Gibson
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