On Fri, Jan 17, 2020 at 02:58:47PM +0100, Paolo Bonzini wrote: > On 17/01/20 14:40, Michael S. Tsirkin wrote: > > We don't really need v2 just to add a field. Compatibility is maintained > > using feature bits. Adding that is a subject for another patch. > > But I'm not sure I understand why does remote need to know about alignment. > > This patch seems to handle it locally ... > > Because the remote vhost here will not be able to use the synic regions. > If it did, it would have the same overlap problem as vhost-kernel. > > The alignment is needed because, even if you are mapping only [768k,1M) > of a 2M hugepage, you need to mmap [0,2M). You can then discard the > rest, but IIUC if you only mmap [768k,1M) then the kernel will fail the > mmap. > > Paolo
So right now remote will query the fd passed to get the alignment. You are basically saying it's not enough in some cases? -- MST
