Il 07/04/2014 05:55, Michael S. Tsirkin ha scritto:
> + u16 do_pi_niov; /* DataOUT PI Number of iovecs */
> + u16 di_pi_niov; /* DataIN PI Number of iovecs */
So this looks like a somewhat problematic interface to me in that
it talks in terms of iovecs not bytes.
So this perpetuates the assumption that header is in a separate
iov from data (and protection is separate from data).
Arguably virtio doesn't work in terms of iovecs on the guest side so
this naming looks strange.
Further host side, get_vq_descs can in theory split a buffer to multiple
iovecs if it crosses the boundary of a memory region.
One solution is to use byte lengths here, but this does require
that vhost scsi gets rid of layout assumptions generally.
Not sure that's practical for -rc1.
Why does that require that vhost scsi gets rid of layout assumptions?
The interface uses bytes instead of iovecs as the unit, and vhost-scsi
can add the (temporary...) requirement that do_pi_nbytes and
di_pi_nbytes comprise an integer number of iovecs.
Paolo
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