Re: [Qemu-arm] [PATCH v3 4/5] target/arm: Fill in ARMISARegisters for kvm32

[Richard Henderson]

On 11/12/18 1:42 PM, Peter Maydell wrote:
> Adding the following change allowed me to boot:
> 
> diff --git a/target/arm/kvm32.c b/target/arm/kvm32.c
> index 8b2c9b3..2f7df81 100644
> --- a/target/arm/kvm32.c
> +++ b/target/arm/kvm32.c
> @@ -84,9 +84,15 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures 
> *ahcf)
>                            ARM_CP15_REG32(0, 0, 2, 4));
>      err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_isar5,
>                            ARM_CP15_REG32(0, 0, 2, 5));
> -    err |= read_sys_reg32(fdarray[2], &ahcf->isar.id_isar6,
> -                          ARM_CP15_REG32(0, 0, 2, 7));
> -
> +    if (read_sys_reg32(fdarray[2], &ahcf->isar.id_isar6,
> +                          ARM_CP15_REG32(0, 0, 2, 7))) {
> +        /*
> +         * Older kernels don't support reading ID_ISAR6. This register was
> +         * only introduced in ARMv8, so we can assume that it is zero on a
> +         * CPU that a kernel this old is running on.
> +         */
> +        ahcf->isar.id_isar6 = 0;
> +    }

Ah, right, thanks.


r~