On Fri, Jul 22, 2022 at 01:09:30PM +0800, Ming Lei wrote:
> + unsigned long *map = (unsigned long *)&ub->dev_info.flags[0];
> +
> + /* We are not ready to support zero copy */
> + ub->dev_info.flags[0] &= ~UBLK_F_SUPPORT_ZERO_COPY;
> +
> + /*
> + * 128bit flags will be copied back to userspace as feature
> + * negotiation result, so have to clear flags which driver
> + * doesn't support yet, then userspace can get correct flags
> + * (features) to handle.
> + */
> + bitmap_clear(map, __UBLK_F_NR_BITS, 128 - __UBLK_F_NR_BITS);
Please don't do the cast and bitmap ops. In fact I think the current
ABI is rather nasty. To make everyones life easier just use a single
u64 flags, an mark the second one reserved so that we can extent into
it with extra flags or something else. That way normal C operator
leve bitops just work.
> +enum ublk_flag_bits {
> + __UBLK_F_SUPPORT_ZERO_COPY,
> + __UBLK_F_URING_CMD_COMP_IN_TASK,
> + __UBLK_F_NR_BITS,
> +};
Please make these #defines so that userspace can detect if they
exist in a header using #ifdef.
