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Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap
From: |
Peter Crosthwaite |
Subject: |
Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap |
Date: |
Wed, 19 Sep 2012 14:40:03 +1000 |
On Wed, Sep 19, 2012 at 2:32 PM, Edgar E. Iglesias
<address@hidden> wrote:
> On Wed, Sep 19, 2012 at 02:25:48PM +1000, Peter Crosthwaite wrote:
>> Ping for PMM,
>>
>> This is the root case of your block on the SDHCI series - this is a
>> discussion on resolution to bogus infinite looping DMA. For current
>> participants in this discussion, heres our thread on the same topic
>> over in SD land:
>>
>> http://lists.gnu.org/archive/html/qemu-devel/2012-08/msg01017.html
>>
>> With the findings here and acknowledgement that this is a general
>> problem, we either need to declare this issue of scope for SDHCI, or
>> work with these guys (in the immediate future) on the DMA infinite
>> loop problem flagged here. I dont mind if SDHCI+ADMA is the guinea pig
>> here, but can we get a decisive plan for going forward with this issue
>> if it is going to continue to block SDHCI.
>>
>> Thanks to Igor for identifying the overlap between these discussions.
>
> Hi,
>
> A couple of dumb questions.
>
> What is the reason for the blocker? that possible guest dos is worse
> than no functionality at all?
>
> Can't you put the DMA/IO processing into the background?
I dont know a way do do asynchronous DMA unless I am missing something
here. So what happens is we have a device that walks a SG list
synchronously while holding all the locks and stuff being discussed
here. If that SG list infinite loops then crash.
>
> what's the diff between setup of bad descriptors and writing a
> while (1) loop in the guest CPU?
>
While(1) in guest doesnt freeze all of QEMU (monitor still works and
stuff), wheras the DMA ops going in circles does, as locks are taken
by an infinite loop.
Regards,
peter
> Cheers,
> E
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, (continued)
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Jan Kiszka, 2012/09/11
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Avi Kivity, 2012/09/11
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Jan Kiszka, 2012/09/11
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Avi Kivity, 2012/09/11
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Jan Kiszka, 2012/09/11
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Avi Kivity, 2012/09/11
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Jan Kiszka, 2012/09/11
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Avi Kivity, 2012/09/11
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Peter Crosthwaite, 2012/09/19
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Edgar E. Iglesias, 2012/09/19
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap,
Peter Crosthwaite <=
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Avi Kivity, 2012/09/19
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Edgar E. Iglesias, 2012/09/19
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Avi Kivity, 2012/09/19
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Edgar E. Iglesias, 2012/09/19
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Igor Mitsyanko, 2012/09/19
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Avi Kivity, 2012/09/19
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Jan Kiszka, 2012/09/19
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Igor Mitsyanko, 2012/09/19
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Jan Kiszka, 2012/09/11
- Re: [Qemu-devel] [PATCH V3 10/11] vcpu: introduce lockmap, Avi Kivity, 2012/09/11