Re: [kvm-unit-tests PATCH v1 5/5] configure: arm64: Make 'max' the default for --processor

[Andrew Jones <andrew.jones@linux.dev>]

On Fri, Jan 10, 2025 at 01:58:48PM +0000, Alexandru Elisei wrote:
> Newer architecture features are supported by qemu TCG on newer CPUs. When
> writing a test for such architecture features, it is necessary to pass the
> correct -cpu argument to qemu. Make it easier on users and test authors
> alike by making 'max' the default value for --processor. The 'max' CPU
> model contains all the features of the cortex-a57 CPU (the old default), so
> no regression should be possible.
> 
> A side effect is that, by default, the compiler will not receive a -mcpu
> argument for compiling the code. The expectation is that this is fine,
> since support for -mcpu=$PROCESSOR has only been added for arm64 in the
> last commit.
> 
> The default for arm (cortex-a15) has been kept unchanged, because passing
> --processor=max will cause compilation to break. If the user wants the qemu
> CPU model to be 'max', the user will also have to supply a suitable compile
> CPU target via --cflags=-mcpu=<cpu> configure option.
> 
> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
> ---
>  configure | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/configure b/configure
> index 46964d36a7d8..3ab0ec208e10 100755
> --- a/configure
> +++ b/configure
> @@ -14,7 +14,7 @@ function get_default_processor()
>          default_processor="cortex-a15"
>          ;;
>      "arm64" | "aarch64")
> -        default_processor="cortex-a57"
> +        default_processor="max"
>          ;;
>      *)
>          default_processor=$arch
> -- 
> 2.47.1
>

Another reason to introduce a new parameter (qemu_cpu) is that we can also
change arm32 to 'max', reducing divergence between arm32 and arm64.

Thanks,
drew