Re: [Qemu-devel] [RFC 0/2] ARM virt: Support up to 256 PCIe buses

[Laszlo Ersek <lersek@redhat.com>]

On 05/24/18 16:09, Auger Eric wrote:
> Hi Laszlo,
> 
> On 05/24/2018 03:59 PM, Laszlo Ersek wrote:
>> On 05/24/18 15:07, 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".
>>
>> Ah, OK, I didn't know that.
>>
>>> So we can handle those kernels by just not putting ECAM
>>> above 4G if highmem is false.
>>
>> The problem is we can have a combination of 32-bit UEFI firmware (which
>> certainly lacks LPAE) and a 32-bit kernel which supports LPAE.
> 
> Is it what happens with the FW you provided to me? There is no LPAE in it?

That's the case, to my knowledge.

Thanks
Laszlo