Re: Qemu v9.0.2: Boot failed qemu-arm with Linux next-20241017 tag.

["Arnd Bergmann" <arnd@arndb.de>]

On Wed, Oct 23, 2024, at 19:47, Alex Bennée wrote:
>> On Sun, Oct 20, 2024, at 17:39, Naresh Kamboju wrote:
>> On non-LPAE arm32, this broke the existing behavior for
>> large 32-bit memory sizes. The obvious fix is to change
>> back the PAGE_MASK definition for 32-bit arm to a signed
>> number.
>
> Agreed. However I think we were masking a calling issue that:
>
>     /* Actual RAM size depends on initial RAM and device memory settings */
>     [VIRT_MEM] =                { GiB, LEGACY_RAMLIMIT_BYTES },
>
> And:
>
>   -m 4G
>
> make no sense with no ARM_LPAE (which the kernel didn't have) but if you
> pass -machine virt,gic-version=3,highmem=off (the default changed awhile
> back) you will get a warning:
>
>   qemu-system-arm: Addressing limited to 32 bits, but memory exceeds it 
> by 1073741824 bytes
>
> but I guess that didn't trigger for some reason before this patch?

I did not look at the full log, but I don't think there is a
problem between kernel and qemu, this is just a kernel regression
that can happen on any real or virtual platform with a lot of
memory.

I would guess that "highmem=off" was not even set here, so
there was probably no warning, and you would still see the
same kernel bug with qemu-system-aarch64 and its larger
limit for highmem=off.

      Arnd