Re: [PATCH v2 net-next 1/9] xdp: introduce mb in xdp_buff/xdp_frame

On 9/7/20 12:02 PM, Jesper Dangaard Brouer wrote:

quoted

ok, is there any alignment requirement? can frame_sz be number of 32-bit
words? I believe bit shifts are cheap.

No that is not possible, because some drivers and generic-XDP have a
fully dynamic frame_sz.

frame_sz represents allocated memory right? What is the real range that
needs to be supported for frame_sz? Surely there is some upper limit,
and I thought it was 64kB.

Allocated memory will not be on an odd number, so fair to assume at a
minimum it is a multiple of 2. correct? At a minimum we should be able
to shift frame_sz by 1 which now covers 64kB in a u16.