On 01/04/2012 06:04 AM, Alexander Graf wrote: > > > On 04.01.2012, at 11:33, Avi Kivity <[email protected]> wrote: > >> On 01/03/2012 04:13 PM, Alexander Graf wrote: >>> On 03.01.2012, at 15:01, Avi Kivity wrote: >>> >>>> On 12/31/2011 08:16 AM, Liu Yu wrote: >>>>> Add a new field opt_feature in struct kvm_ppc_pvinfo >>>>> to tell userspace whether it support hcall idle. >>>>> >>>>> diff --git a/include/linux/kvm.h b/include/linux/kvm.h >>>>> index c107fae..5af21f3 100644 >>>>> --- a/include/linux/kvm.h >>>>> +++ b/include/linux/kvm.h >>>>> @@ -426,9 +426,12 @@ struct kvm_ppc_pvinfo { >>>>> /* out */ >>>>> __u32 flags; >>>>> __u32 hcall[4]; >>>>> - __u8 pad[108]; >>>>> + __u32 opt_features; >>>>> + __u8 pad[104]; >>>>> }; >>>>> >>>>> +#define KVM_PPC_PVINFO_HAS_EV_IDLE (1<<0) >>>>> + >>>>> >>>> >>>> Needs to be documented, plus a KVM_CAP so userspace can discover that >>>> this feature is available, >>> >>> Not if we put the bit into flags. Then user space can just check the flags >>> bitmap and know that it's there regardless of capabilities, because older >>> kernels will set the bit to 0. >> >> It needs to detect that opt_features is available during compile time >> (qemu copies headers, but we don't want to force everyone to do that). > > The point is that we don't need opt_features. We already have a fearure > bitmap in the struct.
Even if we did for whatever reason want a new field, the entire struct is zeroed currently, so we only need a flag if we need to distinguish "field is zero" from "field is not valid". -Scott -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
