[PATCH 2/5] arm: qemu: enable LPAE on 32-bit

[Ard Biesheuvel]

On Sun, 7 Jun 2020 at 13:03, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> Am June 7, 2020 8:59:00 AM UTC schrieb Ard Biesheuvel <ardb at kernel.org>:
> >On Sat, 6 Jun 2020 at 22:49, Heinrich Schuchardt <xypron.glpk at gmx.de>
> >wrote:
> >>
> >> On 6/6/20 10:32 PM, Heinrich Schuchardt wrote:
> >> > On 6/6/20 7:15 PM, Ard Biesheuvel wrote:
> >> >> QEMU's mach-virt machine only supports selecting CPU models that
> >> >> implement the virtualization extensions, and are therefore
> >guaranteed
> >> >> to support LPAE as well.
> >> >
> >> > I wonder why
> >> > qemu-system-arm -machine virt -cpu help
> >> > lists cortex-a9 (which is not LPAE enabled).
> >> >
> >> > But when I try to use it I get
> >> > qemu-system-arm: mach-virt: CPU type cortex-a9-arm-cpu not
> >supported
> >> > This looks like a missing feature in QEMU.
> >> >
> >
> >This is not a missing feature. The virt board uses PSCI for powerdown
> >and reset, and to bring up secondary cores.
> >PSCI requires the HVC instruction, which is only available if the virt
> >extensions are implemented.
>
> By missing feature I meant  -cpu help output should be filtered according to the -machine value if provided.
>


Ah fair enough. Yes, that would be useful.

Unfortunately, ARM does not permit me to contribute to QEMU, so
hopefully someone else can take this on.