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From: Auger Eric <eric.auger@redhat.com>
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Date: Thu, 24 May 2018 15:10:41 +0200
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Subject: Re: [Qemu-devel] [RFC 0/2] ARM virt: Support up to 256 PCIe buses
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To: Peter Maydell <peter.maydell@linaro.org>, Laszlo Ersek <lersek@redhat.com>
Cc: Eric Auger <eric.auger.pro@gmail.com>, QEMU Developers <qemu-devel@nongnu.org>, qemu-arm <qemu-arm@nongnu.org>, Wei Huang <wei@redhat.com>, Andrew Jones <drjones@redhat.com>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, Shannon Zhao <zhaoshenglong@huawei.com>

Hi Peter, Laszlo,

On 05/24/2018 03:07 PM, Peter Maydell wrote:
> On 24 May 2018 at 13:59, Laszlo Ersek <lersek@redhat.com> wrote:
>> On 05/24/18 11:11, Peter Maydell wrote:
>>> Won't it also break a guest which is just Linux loaded not via
>>> firmware which is an aarch32 kernel without LPAE support?
>>
>> Does such a thing exist? (I honestly have no clue.)
> 
> Yes, it does; LPAE isn't a mandatory kernel config option.
> This is why we have the machine 'highmem' option, so that
> we can run on those kernels by not putting anything above
> the 4G boundary. Looking back at the history on that, we
> opted at the time for "default to highmem on, and if you're
> running an non-lpae kernel you need to turn it off manually".
> So we can handle those kernels by just not putting ECAM
> above 4G if highmem is false.

Actually that's what my series does. If highmem=off then we use the
legacy ECAM.

Thanks

Eric
> 
> thanks
> -- PMM
>