Avi Kivity wrote:
> Beth Kon wrote:
>> Signed-off-by: Beth Kon <eak@xxxxxxxxxx>
>>
>>
>
> Please write a few words on what this patch does and why.
>
>> ---
>> arch/x86/include/asm/kvm.h | 1 +
>> arch/x86/kvm/i8254.c | 24 +++++++++++++++++++-----
>> arch/x86/kvm/i8254.h | 3 ++-
>> arch/x86/kvm/x86.c | 5 ++++-
>> 4 files changed, 26 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
>> index 708b9c3..3c44923 100644
>> --- a/arch/x86/include/asm/kvm.h
>> +++ b/arch/x86/include/asm/kvm.h
>> @@ -235,6 +235,7 @@ struct kvm_guest_debug_arch {
>>
>> struct kvm_pit_state {
>> struct kvm_pit_channel_state channels[3];
>> + u8 hpet_legacy_mode;
>> };
>>
>
> This changes the ABI, breaking older binaries running on newer kernels,
> or newer binaries running on older kernels.
As we have KVM_CREATE_PIT2 now, which includes struct kvm_pit_config
with a lot of unused flags, it should be straightforward to negotiate
the kvm_pit_state format between kernel and user space: kernel
advertises support for the new one via capability, user space requests
it via a bit in kvm_pit_state.flags.
Jan
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