On Mon, Apr 12, 2021 at 5:37 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
>
> 在 2021/4/12 下午4:02, Yongji Xie 写道:
> > On Mon, Apr 12, 2021 at 3:16 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
> >>
> >> 在 2021/4/9 下午4:02, Yongji Xie 写道:
> >>>>>>> +};
> >>>>>>> +
> >>>>>>> +struct vduse_dev_config_data {
> >>>>>>> + __u32 offset; /* offset from the beginning of config space */
> >>>>>>> + __u32 len; /* the length to read/write */
> >>>>>>> + __u8 data[VDUSE_CONFIG_DATA_LEN]; /* data buffer used to read/write */
> >>>>>> Note that since VDUSE_CONFIG_DATA_LEN is part of uAPI it means we can
> >>>>>> not change it in the future.
> >>>>>>
> >>>>>> So this might suffcient for future features or all type of virtio devices.
> >>>>>>
> >>>>> Do you mean 256 is no enough here？
> >>>> Yes.
> >>>>
> >>> But this request will be submitted multiple times if config lengh is
> >>> larger than 256. So do you think whether we need to extent the size to
> >>> 512 or larger?
> >>
> >> So I think you'd better either:
> >>
> >> 1) document the limitation (256) in somewhere, (better both uapi and doc)
> >>
> > But the VDUSE_CONFIG_DATA_LEN doesn't mean the limitation of
> > configuration space. It only means the maximum size of one data
> > transfer for configuration space. Do you mean document this?
>
>
> Yes, and another thing is that since you're using
> data[VDUSE_CONFIG_DATA_LEN] in the uapi, it implies the length is always
> 256 which seems not good and not what the code is wrote.
>
How about renaming VDUSE_CONFIG_DATA_LEN to VDUSE_MAX_TRANSFER_LEN?
Thanks,
Yongji
