On Wed, Jun 01, 2011 at 05:51:54PM +0300, Avi Kivity wrote: > On 06/01/2011 05:36 PM, Michael S. Tsirkin wrote: > >> > >> So, if I am going to give this liberty with buffers to the driver, I > >> _have_ to keep the size information. Otherwise, I agree that it is > >> redundant and I will remove it. What poison do you prefer? > >> > > > >Ah, I think I understand now. Both sense and data have in > >fields that might only be used partially? > >In that case I think I agree: it's best to require the use of separate > >buffers for them, in this way used len will give you useful information > >and you won't need sense_len and data_len: just a flag to > >mark the fact that there *is* a sense buffer following. > >And the num field does that. > > > Do you mean to use the virtio iovec length to determine information > about the message (like splitting it into buffers)?
Exactly the reverse :) > I think that's a bad idea. Splitting into buffers is a function of > memory management. For example, a driver in userspace (or a nested > guest) will have additional fragmentation into 4K pages after it > passes through the iommu. > > Let's not mix layers here. Right. If there are two buffers of variable length there should be two add_buf calls. > -- > error compiling committee.c: too many arguments to function
