On 2020/8/5 上午11:28, Carter Li 李通洲 wrote:
>> diff --git a/src/include/liburing.h b/src/include/liburing.h
>> index 0505a4f..82c2980 100644
>> --- a/src/include/liburing.h
>> +++ b/src/include/liburing.h
>> @@ -56,6 +56,9 @@ struct io_uring {
>> struct io_uring_sq sq;
>> struct io_uring_cq cq;
>> unsigned flags;
>> + unsigned flags_internal;
>> + unsigned features;
>> + unsigned pad[4];
>> int ring_fd;
>> };
>
> Won't it break existing code runs on newer kernel?
io_uring is a structure that used in userspace. It breaks the API
with existing compiled application. So I have changed the soname
to 2.0.7.
And for syscall io_uring_enter(), I have added a new feature bit
IORING_FEAT_GETEVENTS_TIMEOUT and io_uring_enter() flag
IORING_ENTER_GETEVENTS_TIMEOUT. Here are 3 cases below:
1) old liburing <-> new kernel: old liburing can not pass the flag
IORING_ENTER_GETEVENTS_TIMEOUT, so new kernel will parse the arguments
the original way.
2) new liburing <-> old kernel: feature IORING_FEAT_GETEVENTS_TIMEOUT
not supported, liburing will do things like before.
3) new liburing <-> new kernel: feature IORING_FEAT_GETEVENTS_TIMEOUT
supported, liburing pass the new arguments with the flag
IORING_ENTER_GETEVENTS_TIMEOUT which helps kernel parse the arguments
correctly.
Thanks,
Jiufei.
> Won't it break code compiled with new liburing but runs on older kernel?
>
> IMO In this case, a new syscall `io_uring_setup2` is required at least.
>
> Regards,
> Carter
>
