Re: [PATCH v4] xen/arm: Allow QEMU platform to be built with GICv2

[Dongjiu Geng <gengdongjiu1@xxxxxxxxx>]

Bertrand Marquis <Bertrand.Marquis@xxxxxxx> 于2022年1月17日周一 19:38写道：
>
> Hi,
>
> > On 17 Jan 2022, at 11:12, Dongjiu Geng <gengdongjiu1@xxxxxxxxx> wrote:
> >
> > Bertrand Marquis <Bertrand.Marquis@xxxxxxx> 于2022年1月17日周一 17:00写道：
> >>
> >> Hi,
> >>
> >>> On 17 Jan 2022, at 06:40, Dongjiu Geng <gengdongjiu1@xxxxxxxxx> wrote:
> >>>
> >>> It turns out that QEMU has been supporting GICv2 virtualization since
> >>> v3.1.0. So remove the dependencies on GICv3. If we want to use GICv3,
> >>> we can select the QEMU_LEGACY configuration.
> >>
> >> I am bit puzzled by this change introducing a legacy option actually 
> >> selecting the newest GIC interface.
> >>
> >> Can’t we do the opposite and introduce a QEMU_GICV2 instead ?
> >>
> >> Also why do we need to remove gic-v3 support ? The code should actually 
> >> select which gic to use depending on the device tree.
> >
> > QEMU platfrom only select GICv3,  so I remove this limitation,  let
> > user or developer selects gic version is better.
>
> This is where I am lost, the code is actually always compiling gic-v2 support 
> in unless new vgic is selected (see arch/arm/Makefile).

Yes， so can I think you do not have concern for this patch?

>
> Cheers
> Bertrand
>
> >
> >>
> >> Regards
> >> Bertrand
> >>
> >>>
> >>> Signed-off-by: Dongjiu Geng <gengdongjiu1@xxxxxxxxx>
> >>> ---
> >>> xen/arch/arm/platforms/Kconfig | 10 +++++++++-
> >>> 1 file changed, 9 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/xen/arch/arm/platforms/Kconfig 
> >>> b/xen/arch/arm/platforms/Kconfig
> >>> index c93a6b2756..41e82a42ee 100644
> >>> --- a/xen/arch/arm/platforms/Kconfig
> >>> +++ b/xen/arch/arm/platforms/Kconfig
> >>> @@ -13,7 +13,15 @@ config ALL_PLAT
> >>>      automatically select any of the related drivers.
> >>>
> >>> config QEMU
> >>> -     bool "QEMU aarch virt machine support"
> >>> +     bool "QEMU aarch virt machine support >= v3.1.0"
> >>> +     depends on ARM_64
> >>> +     select HAS_PL011
> >>> +     ---help---
> >>> +     Enable all the required drivers for QEMU aarch64 virt emulated
> >>> +     machine.
> >>> +
> >>> +config QEMU_LEGACY
> >>> +     bool "QEMU aarch virt machine support < v3.1.0"
> >>>      depends on ARM_64
> >>>      select GICV3
> >>>      select HAS_PL011
> >>> --
> >>> 2.25.1
>