Re: [PATCH] xen/arm: fix the build error for GIC

[Julien Grall <julien@xxxxxxx>]

Hello,

On 22/12/2021 09:38, Dongjiu Geng wrote:
> when enable CONFIG_NEW_VGIC in ARM64 QEMU Platform, it will build failed.
> so fix it and make it can select GICV2.
Last time I checked QEMU, it was only able to support GICv3 
virtualization. Has it changed since?
> Signed-off-by: Dongjiu Geng <gengdongjiu1@xxxxxxxxx>
> ---
> $ make dist-xen XEN_TARGET_ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j10
> make -C xen install
> make[1]: Entering directory 
> '/home/workspace/gengdongjiu/old_machine/XEN/xen/xen'
> make -f /home/workspace/gengdongjiu/old_machine/XEN/xen/xen/tools/kconfig/Makefile.kconfig 
> ARCH=arm64 SRCARCH=arm HOSTCC="gcc" HOSTCXX="g++" syncconfig
> make[2]: Entering directory 
> '/home/workspace/gengdongjiu/old_machine/XEN/xen/xen'
> gcc -Wp,-MD,tools/kconfig/.conf.o.d      -c -o tools/kconfig/conf.o 
> tools/kconfig/conf.c
> gcc -Wp,-MD,tools/kconfig/.confdata.o.d      -c -o tools/kconfig/confdata.o 
> tools/kconfig/confdata.c
> gcc -Wp,-MD,tools/kconfig/.expr.o.d      -c -o tools/kconfig/expr.o 
> tools/kconfig/expr.c
> flex -otools/kconfig/lexer.lex.c -L tools/kconfig/lexer.l
> bison -o tools/kconfig/parser.tab.c --defines=tools/kconfig/parser.tab.h -t -l 
> tools/kconfig/parser.y
> gcc -Wp,-MD,tools/kconfig/.preprocess.o.d      -c -o tools/kconfig/preprocess.o 
> tools/kconfig/preprocess.c
> gcc -Wp,-MD,tools/kconfig/.symbol.o.d      -c -o tools/kconfig/symbol.o 
> tools/kconfig/symbol.c
> gcc -Wp,-MD,tools/kconfig/.lexer.lex.o.d     -I 
> /home/workspace/gengdongjiu/old_machine/XEN/xen/xen/tools/kconfig -c -o 
> tools/kconfig/lexer.lex.o tools/kconfig/lexer.lex.c
> gcc -Wp,-MD,tools/kconfig/.parser.tab.o.d     -I 
> /home/workspace/gengdongjiu/old_machine/XEN/xen/xen/tools/kconfig -c -o 
> tools/kconfig/parser.tab.o tools/kconfig/parser.tab.c
> gcc  -o tools/kconfig/conf tools/kconfig/conf.o tools/kconfig/confdata.o 
> tools/kconfig/expr.o tools/kconfig/lexer.lex.o tools/kconfig/parser.tab.o 
> tools/kconfig/preprocess.o tools/kconfig/symbol.o
> tools/kconfig/conf  --syncconfig Kconfig
>
> WARNING: unmet direct dependencies detected for GICV3
>    Depends on [n]: ARM_64 [=y] && !NEW_VGIC [=y]
>    Selected by [y]:
>    - QEMU [=y] && <choice> && ARM_64 [=y]
>
> WARNING: unmet direct dependencies detected for GICV3
>    Depends on [n]: ARM_64 [=y] && !NEW_VGIC [=y]
>    Selected by [y]:
>    - QEMU [=y] && <choice> && ARM_64 [=y]
>
> WARNING: unmet direct dependencies detected for GICV3
>    Depends on [n]: ARM_64 [=y] && !NEW_VGIC [=y]
>    Selected by [y]:
>    - QEMU [=y] && <choice> && ARM_64 [=y]
> make[2]: Leaving directory '/home/workspace/gengdongjiu/old_machine/XEN/xen/xen'
> make -f Rules.mk _install
> make[2]: Entering directory 
> '/home/workspace/gengdongjiu/old_machine/XEN/xen/xen'
> ---
>   xen/arch/arm/platforms/Kconfig | 1 -
>   1 file changed, 1 deletion(-)
>
> diff --git a/xen/arch/arm/platforms/Kconfig b/xen/arch/arm/platforms/Kconfig
> index c93a6b2756..6d3ee99456 100644
> --- a/xen/arch/arm/platforms/Kconfig
> +++ b/xen/arch/arm/platforms/Kconfig
> @@ -15,7 +15,6 @@ config ALL_PLAT
>   config QEMU
>         bool "QEMU aarch virt machine support"
>         depends on ARM_64
> -       select GICV3
Assuming you can use Xen with GICv2 on QEMU, then this change is OK. But 
we are at risk to expose it again via another platform.
So I think it would be better to also to add a dependency !GICV3 for 
NEW_VGIC.
Cheers,

--
Julien Grall