[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v4] xen/arm: Allow QEMU platform to be built with GICv2
Bertrand Marquis <Bertrand.Marquis@xxxxxxx> 于2022年1月18日周二 16:48写道: > > Hi Dongju, > > > On 18 Jan 2022, at 08:45, Dongjiu Geng <gengdongjiu1@xxxxxxxxx> wrote: > > > > Julien Grall <julien@xxxxxxx> 于2022年1月17日周一 22:16写道: > >> > >> Hi, > >> > >> On 17/01/2022 10:40, Dongjiu Geng wrote: > >>> It turns out that QEMU has been supporting GICv2 virtualization since > >>> v3.1.0. So remove the dependencies on GICv3. > >> > >> > >> Technically, the current form of CONFIG_QEMU allows the same binary to > >> boot on QEMU with GICv2 or GICv3. > >> > >>> If we want to use GICv3, > >>> we can select the QEMU_LEGACY configuration. > >> > >> AFAIK, GICv3 is not a legacy feature... So it feels a bit odd to name it > >> like that (see more below). > > > > Legacy means QEMU platform only supports GICV3, now it can support > > both GICv2 and GICv3. The scope of support has been expanded > > Not mean GICv3 is a legacy feature. > > You might be misleading a bit here. > In the current configuration, Xen support GICv2, GICv3 and vgic. > The only thing not supported is actually the new VGIC but this is an > unsupported feature not fully functional which shall be used with caution. > > What issue exactly do you have in Qemu configured for gicv2 when you use the > default configuration ? I want to use NEW_VGIC with GICv2, but QEMU only select GICV3, when GICv3 is select, the NEW_VGIC can not be used. I try the NEW_VGIC with GICv2, not found issue. so I want to remove this limitation. If you think we should not support NEW_VGIC feature, we can ignore this patch. thanks! > > Cheers > 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" > >> > >> This is a bit misleading. A user may select this thinking that this will > >> select GICv3. However, this will not. > >> > >> This also raises the question of what is the default GIC version in QEMU > >> (i.e. if you don't pass anything on the command line)? If this is GICv3, > >> then I am afraid that this patch would be a no-go for me. > >> > >> Looking at overall discussion, you seem to push the patch only to allow > >> building a tiny Xen for QEMU and the new vGIC. > >> > >> The default Xen (i.e. make defconfig) will also work on QEMU. Given that > >> the new vGIC is a still in development, I am seriously considering to > >> say that if you want to try it then you have to use the default > >> configuration. > >> > >> @Dongjiu, is there any reason why you want to use the tiny QEMU config > >> rather than the default configuration? > > > > Hi Julien, thanks for the reply, I do not use the tiny QEMU config. I > > used the default configuration and selected the platform as QEMU. > > But QEMU platform only slects GICV3, so I submit this patch to remove > > the limitation because I want to use VGIC. VGIC can already support > > GICv2 now. > > > >> > >> @Bertrand, @Stefano, what do you think? > >> > >> Cheers, > >> > >> -- > >> Julien Grall >
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