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Re: [Qemu-devel] powerpc: Clear user CPU feature bits if TM is disabled
From: |
Michael Ellerman |
Subject: |
Re: [Qemu-devel] powerpc: Clear user CPU feature bits if TM is disabled at runtime |
Date: |
Wed, 06 Apr 2016 08:40:27 +1000 |
User-agent: |
K-9 Mail for Android |
On 5 April 2016 7:56:23 pm AEST, Benjamin Herrenschmidt <address@hidden> wrote:
>On Tue, 2016-04-05 at 19:35 +1000, Michael Ellerman wrote:
>> Shouldn't we be clearing the user feature there too?
>>
>> The ibm_pa_features array and the logic in scan_features() knows to
>> flip the
>> cpu_user_features bits, it was just never updated to handle
>> cpu_user_features2.
>>
>> So it seems to me that's where the bug is.
>
>I was about to make the same comment but then realized we are trying to
>clear *2* bits. And since that logic will also, I think, set the bits
>when the corresponding pa-feature is present, it means we will also set
>those 2 bits if we put both in the mask...
That's what we want in this case. The 2nd bit describes Linux's behaviour of
aborting active transactions in syscalls, so kernels that have that bit defined
should be setting/clearing it in lock step with the main TM bit.
cheers
--
Sent from my Android phone with K-9 Mail. Please excuse my brevity.
- Re: [Qemu-devel] PR KVM and TM issues, Anton Blanchard, 2016/04/04
- [Qemu-devel] [PATCH] powerpc: Clear user CPU feature bits if TM is disabled at runtime, Anton Blanchard, 2016/04/04
- [Qemu-devel] [PATCH 1/3] powerpc: scan_features() updates incorrect bits, Anton Blanchard, 2016/04/14
- Re: [Qemu-devel] [1/3] powerpc: scan_features() updates incorrect bits, Michael Ellerman, 2016/04/18
- [Qemu-devel] [PATCH v2 1/3] powerpc: scan_features() updates incorrect bits for REAL_LE, Michael Ellerman, 2016/04/18
- Re: [Qemu-devel] [v2, 1/3] powerpc: scan_features() updates incorrect bits for REAL_LE, Michael Ellerman, 2016/04/19
[Qemu-devel] [PATCH 2/3] powerpc: Update cpu_user_features2 in scan_features(), Anton Blanchard, 2016/04/14
[Qemu-devel] [PATCH 3/3] powerpc: Update TM user feature bits in scan_features(), Anton Blanchard, 2016/04/14