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Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel p
From: |
Alexander Graf |
Subject: |
Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size |
Date: |
Sun, 4 Mar 2012 21:25:30 +0100 |
On 04.03.2012, at 21:21, Andreas Färber <address@hidden> wrote:
> Am 04.03.2012 19:46, schrieb Alexander Graf:
>>
>>
>> On 04.03.2012, at 17:46, Andreas Färber <address@hidden> wrote:
>>
>>> Am 04.03.2012 12:53, schrieb Benjamin Herrenschmidt:
>>>> On Sun, 2012-03-04 at 12:49 +0200, Avi Kivity wrote:
>>>>> On 02/28/2012 11:48 PM, Benjamin Herrenschmidt wrote:
>>>>>> On Tue, 2012-02-28 at 14:32 +0200, Avi Kivity wrote:
>>>>>>
>>>>>>> What if TARGET_PAGE_SIZE > getpagesize()? Or is that impossible?
>>>>>>
>>>>>> We have yet to encounter such a case. It's not currently possible on
>>>>>> power (some old embedded chips could do 1K and 2K page sizes in the TLB
>>>>>> iirc but we never supported that in Linux and it's being phased out in
>>>>>> HW).
>>>>>>
>>>>>> I suggest that gets dealt with when/if it needs to, which means probably
>>>>>> never :-)
>>>>>
>>>>> Doesn't ppc support both 4k and 64k pages? Suppose you run a 4k guest
>>>>> on a 64k host?
>>>>>
>>>>> Maybe I'm misremembering or misunderstanding something.
>>>
>>>> TARGET_PAGE_SIZE in qemu is always 4k for powerpc, it's a compile time
>>>> #define.
>>>
>>> Except for ppcemb-softmmu (1k), which is irrelevant for KVM AFAIU.
>>>
>>> Maybe just add an assert and be done with it?
>>
>> Assert for what? Linux page size of 64k is something perfectly normal on
>> ppc. The hardware can always do at least 4k maps however.
>
> g_assert(TARGET_PAGE_SIZE <= getpagesize())
>
> Just declare the above case as unsupported and abort if we encounter it.
What I'm trying to tell you is that it's the default case on book3s ppc! ;)
Alex
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Avi Kivity, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Benjamin Herrenschmidt, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Avi Kivity, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Andreas Färber, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Alexander Graf, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Andreas Färber, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size,
Alexander Graf <=
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Andreas Färber, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Alexander Graf, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Benjamin Herrenschmidt, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Alexander Graf, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Andreas Färber, 2012/03/04
- Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size, Benjamin Herrenschmidt, 2012/03/04