Am 29.01.2019 um 12:18 hat Vladimir Sementsov-Ogievskiy geschrieben:
> 29.01.2019 13:32, Stefan Hajnoczi wrote:
> > On Tue, Jan 29, 2019 at 6:24 PM Vladimir Sementsov-Ogievskiy
> > <vsement...@virtuozzo.com> wrote:
> >> 29.01.2019 6:31, Stefan Hajnoczi wrote:
> >>> On Fri, Jan 25, 2019 at 07:46:01PM +0300, Vladimir Sementsov-Ogievskiy
> >>> wrote:
> >> Hmm. In this case we definitely will have tiny extra memory usage, but we
> >> gain beautiful
> >> readability.
> >>
> >> So, like this:
> >>
> >> diff --git a/include/qemu/iov.h b/include/qemu/iov.h
> >> index 5f433c7768..53de1b38bb 100644
> >> --- a/include/qemu/iov.h
> >> +++ b/include/qemu/iov.h
> >> @@ -134,9 +134,31 @@ typedef struct QEMUIOVector {
> >> struct iovec *iov;
> >> int niov;
> >> int nalloc;
> >> - size_t size;
> >> + union {
> >> + struct {
> >> + void *__unused_iov_base;
> >
> > This could be struct iovec *iov for nalloc > 0 users. Must resist
> > hackiness! :)
>
> can't be iov, gcc complains:
> include/qemu/iov.h:139:27: error: duplicate member ‘iov’
> struct iovec *iov;
I think Stefan meant moving the existing iov here. But then we would
have to make sure that it's never used for local qiovs, which would
probably involve touching a lot more code.
Your original suggestion to put nalloc there looks a bit more practical
if we want to save those bytes.
Kevin
