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Re: [Qemu-arm] [PATCH v3 0/7] Runtime pagesize computation
From: |
Peter Maydell |
Subject: |
Re: [Qemu-arm] [PATCH v3 0/7] Runtime pagesize computation |
Date: |
Tue, 11 Oct 2016 13:18:07 -0700 |
On 11 October 2016 at 12:20, Richard Henderson <address@hidden> wrote:
> On 10/11/2016 12:08 PM, Peter Maydell wrote:
>> I would ideally have liked to finalize things much later, but
>> this is in practice hugely difficult because so many things
>> (in particular all the address space/memory system code)
>> assume the target page size is known.
> Unfortunate. I suppose that 4k is still better than 1k, but
> I was hoping to get 16k or 64k (or higher) when the OS is
> configured to use such. I.e. totally dynamically configurable
> upon write to the appropriate cpu register.
I think that would run into problems with migration:
the migration stream all works in guest-pages of ram and
a mismatch means migration doesn't work.
> Given how the memory subsystem already dynamically reconfigures
> itself for changes in address_space topology, I assumed page size
> changes would be trivial and fall out naturally.
The trouble is that all the data structures work in terms
of page sizes (even though we support sub-page allocations
those are still done by carving up a page-size chunk).
It could probably be done but it looked like a gargantuan
task so I decided this was a better compromise.
thanks
-- PMM
- [Qemu-arm] [PATCH v3 7/7] hw/arm/virt: Set minimum_page_bits to 12, (continued)
- [Qemu-arm] [PATCH v3 5/7] migration/savevm.c: migrate non-default page size, Peter Maydell, 2016/10/11
- [Qemu-arm] [PATCH v3 4/7] cpu: Support a target CPU having a variable page size, Peter Maydell, 2016/10/11
- [Qemu-arm] [PATCH v3 2/7] exec.c: Remove static allocation of sub_section of sub_page, Peter Maydell, 2016/10/11
- Re: [Qemu-arm] [PATCH v3 0/7] Runtime pagesize computation, Peter Maydell, 2016/10/11
- Re: [Qemu-arm] [PATCH v3 0/7] Runtime pagesize computation, Richard Henderson, 2016/10/11
- Re: [Qemu-arm] [PATCH v3 0/7] Runtime pagesize computation,
Peter Maydell <=
- Re: [Qemu-arm] [Qemu-devel] [PATCH v3 0/7] Runtime pagesize computation, no-reply, 2016/10/11
- Re: [Qemu-arm] [PATCH v3 0/7] Runtime pagesize computation, Peter Maydell, 2016/10/21