When the host doesn't support 32bit guests, the kvmtool fails without a proper message on what is wrong. i.e, $ lkvm run -c 1 Image --aarch32 # lkvm run -k Image -m 256 -c 1 --name guest-105618 Fatal: Unable to initialise vcpu Given that there is no other easy way to check if the host supports 32bit guests, it is always good to report this by checking the capability, rather than leaving the users to hunt this down by looking at the code! After this patch: $ lkvm run -c 1 Image --aarch32 # lkvm run -k Image -m 256 -c 1 --name guest-105695 Fatal: 32bit guests are not supported Cc: Will Deacon <will@xxxxxxxxxx> Reported-by: Sami Mujawar <sami.mujawar@xxxxxxx> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx> --- arm/kvm-cpu.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c index 554414f..2acecae 100644 --- a/arm/kvm-cpu.c +++ b/arm/kvm-cpu.c @@ -46,6 +46,10 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id) .features = ARM_VCPU_FEATURE_FLAGS(kvm, cpu_id) }; + if (kvm->cfg.arch.aarch32_guest && + !kvm__supports_extension(kvm, KVM_CAP_ARM_EL1_32BIT)) + die("32bit guests are not supported\n"); + vcpu = calloc(1, sizeof(struct kvm_cpu)); if (!vcpu) return NULL; -- 2.24.1