From: Scott Wood <scottwood@freescale.com>
To: Alexander Graf <agraf@suse.de>
Cc: "<kvm-ppc@vger.kernel.org>" <kvm-ppc@vger.kernel.org>,
"<kvm@vger.kernel.org>" <kvm@vger.kernel.org>
Subject: Re: [PATCH] KVM: PPC: e500: Don't hardcode PIR=0
Date: Fri, 02 Sep 2011 19:35:25 +0000 [thread overview]
Message-ID: <4E612FFD.8000300@freescale.com> (raw)
In-Reply-To: <1C0EA3C2-5994-4AEA-92C0-346981AB994D@suse.de>
On 09/02/2011 02:23 PM, Alexander Graf wrote:
>
> On 02.09.2011, at 20:14, Scott Wood wrote:
>
>> On 09/02/2011 10:12 AM, Alexander Graf wrote:
>>>
>>> Am 02.09.2011 um 01:08 schrieb Scott Wood <scottwood@freescale.com>:
>>>
>>>> Signed-off-by: Scott Wood <scottwood@freescale.com>
>>>
>>> Patch description missing.
>>
>> It's not missing, it's just brief. :-)
>>
>> I suppose you could add "The hardcoded behavior prevents SMP support.
>> QEMU shall specify the vcpu's PIR as the vcpu id".
>
> Ok, let me get my head around this. Before, PIR was forced to 0 by
> the setup code and set_sregs with PIR != 0 failed. Now it's simply
> vcpu_id which is already the correct value. Why didn't I run into
> this failure? Why did SMP work for me at all then? Shouldn't the
> guest be completely confused and find two CPU 0s?
I was wondering about that myself. It looks like PIR isn't used much in
Linux on e500v2. There's no msgsnd. It's used to for
__secondary_hold_acknowledge, but that has a silent timeout.
-Scott
WARNING: multiple messages have this Message-ID (diff)
From: Scott Wood <scottwood@freescale.com>
To: Alexander Graf <agraf@suse.de>
Cc: "<kvm-ppc@vger.kernel.org>" <kvm-ppc@vger.kernel.org>,
"<kvm@vger.kernel.org>" <kvm@vger.kernel.org>
Subject: Re: [PATCH] KVM: PPC: e500: Don't hardcode PIR=0
Date: Fri, 2 Sep 2011 14:35:25 -0500 [thread overview]
Message-ID: <4E612FFD.8000300@freescale.com> (raw)
In-Reply-To: <1C0EA3C2-5994-4AEA-92C0-346981AB994D@suse.de>
On 09/02/2011 02:23 PM, Alexander Graf wrote:
>
> On 02.09.2011, at 20:14, Scott Wood wrote:
>
>> On 09/02/2011 10:12 AM, Alexander Graf wrote:
>>>
>>> Am 02.09.2011 um 01:08 schrieb Scott Wood <scottwood@freescale.com>:
>>>
>>>> Signed-off-by: Scott Wood <scottwood@freescale.com>
>>>
>>> Patch description missing.
>>
>> It's not missing, it's just brief. :-)
>>
>> I suppose you could add "The hardcoded behavior prevents SMP support.
>> QEMU shall specify the vcpu's PIR as the vcpu id".
>
> Ok, let me get my head around this. Before, PIR was forced to 0 by
> the setup code and set_sregs with PIR != 0 failed. Now it's simply
> vcpu_id which is already the correct value. Why didn't I run into
> this failure? Why did SMP work for me at all then? Shouldn't the
> guest be completely confused and find two CPU 0s?
I was wondering about that myself. It looks like PIR isn't used much in
Linux on e500v2. There's no msgsnd. It's used to for
__secondary_hold_acknowledge, but that has a silent timeout.
-Scott
next prev parent reply other threads:[~2011-09-02 19:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-01 23:08 [PATCH] KVM: PPC: e500: Don't hardcode PIR=0 Scott Wood
2011-09-01 23:08 ` Scott Wood
2011-09-02 1:23 ` [linuxppc-release] " Tabi Timur-B04825
2011-09-02 1:23 ` Tabi Timur-B04825
2011-09-02 15:12 ` Alexander Graf
2011-09-02 15:12 ` Alexander Graf
2011-09-02 18:14 ` Scott Wood
2011-09-02 18:14 ` Scott Wood
2011-09-02 19:23 ` Alexander Graf
2011-09-02 19:23 ` Alexander Graf
2011-09-02 19:35 ` Scott Wood [this message]
2011-09-02 19:35 ` Scott Wood
2011-09-02 19:46 ` Alexander Graf
2011-09-02 19:46 ` Alexander Graf
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