Re: [Qemu-devel] [kvmtool test PATCH 22/24] kvmtool: arm64: Add support for guest physical address size

[Will Deacon]

On Fri, Jun 29, 2018 at 12:15:42PM +0100, Suzuki K Poulose wrote:
> Add an option to specify the physical address size used by this
> VM.
> 
> Signed-off-by: Suzuki K Poulose <address@hidden>
> ---
>  arm/aarch64/include/kvm/kvm-config-arch.h | 5 ++++-
>  arm/include/arm-common/kvm-config-arch.h  | 1 +
>  2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/arm/aarch64/include/kvm/kvm-config-arch.h 
> b/arm/aarch64/include/kvm/kvm-config-arch.h
> index 04be43d..dabd22c 100644
> --- a/arm/aarch64/include/kvm/kvm-config-arch.h
> +++ b/arm/aarch64/include/kvm/kvm-config-arch.h
> @@ -8,7 +8,10 @@
>                       "Create PMUv3 device"),                         \
>       OPT_U64('\0', "kaslr-seed", &(cfg)->kaslr_seed,                 \
>                       "Specify random seed for Kernel Address Space " \
> -                     "Layout Randomization (KASLR)"),
> +                     "Layout Randomization (KASLR)"),                \
> +     OPT_INTEGER('\0', "phys-shift", &(cfg)->phys_shift,             \
> +                     "Specify maximum physical address size (not "   \
> +                     "the amount of memory)"),

Given that this is a shift value, I think the help message could be more
informative. Something like:

        "Specify maximum number of bits in a guest physical address"

I think I'd actually leave out any mention of memory, because this does
actually have an effect on the amount of addressable memory in a way that I
don't think we want to describe in half of a usage message line :)

Will