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Re: [Qemu-devel] [kvmtool test PATCH 24/24] kvmtool: arm: Add support fo
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [kvmtool test PATCH 24/24] kvmtool: arm: Add support for creating VM with PA size |
Date: |
Thu, 5 Jul 2018 08:51:19 +0100 |
On 4 July 2018 at 16:51, Will Deacon <address@hidden> wrote:
> On Wed, Jul 04, 2018 at 03:41:18PM +0100, Marc Zyngier wrote:
>> Not really. Let's say I want my IPA space split in two: memory covers
>> the low 47 bit, and I want MMIO spanning the top 47 bit. With your
>> scheme, you'd end-up with a 47bit IPA space, while you really want 48
>> bits (MMIO space implemented by userspace isn't registered to the
>> kernel).
>
> That still sounds quite niche for a VM. Does QEMU do that?
Not at 47 bits, but we have RAM up to the 256GB mark, and
MMIO above that (including a large PCI window), so the general
arrangement of having the top end of the IPA space not
necessarily be things we've told the kernel about definitely
exists.
thanks
-- PMM