Re: [PATCH v2 1/4] Include new arbitrary limits if not already defined

[Manolo de Medici]

On Mon, Jan 22, 2024 at 6:40 PM Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Mon, 22 Jan 2024 at 17:27, Daniel P. Berrangé <berrange@redhat.com> wrote:
> >
> > On Thu, Jan 18, 2024 at 05:02:23PM +0100, Manolo de Medici wrote:
> > > qemu uses the PATH_MAX and IOV_MAX constants extensively
> > > in the code. Define these constants to sensible values ourselves
> > > if the system doesn't define them already.
> >
> > Please give details of what platform(s) lack these constants
> > in the commit message.
> >
> > Presumably this is a platform that is outside of our normal
> > support build target list, since we have at least build
> > coverage for everything mainstream.
>
> It's GNU Hurd. The patchset isn't threaded, but the cover
> letter is
> https://lore.kernel.org/qemu-devel/CAHP40m=UQ=F1-Vy4-wR18RjqzF9o+8UOjgpUsrTU8QXn=7eAeA@mail.gmail.com/
>
> and you can pick up the other patches in it by searching the list.
>
> > >
> > > Signed-off-by: Manolo de Medici <manolo.demedici@gmail.com>
> > > ---
> > >  include/qemu/osdep.h | 8 ++++++++
> > >  1 file changed, 8 insertions(+)
> > >
> > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> > > index 9a405bed89..9fb6ac5c64 100644
> > > --- a/include/qemu/osdep.h
> > > +++ b/include/qemu/osdep.h
> > > @@ -363,6 +363,14 @@ void QEMU_ERROR("code path is reachable")
> > >  #define TIME_MAX TYPE_MAXIMUM(time_t)
> > >  #endif
> > >
> > > +#ifndef PATH_MAX
> > > +#define PATH_MAX 1024
> > > +#endif
> > > +
> > > +#ifndef IOV_MAX
> > > +#define IOV_MAX 1024
> > > +#endif
> >
> > If we're going to add this, since we should be removing the
> > later duplication:
> >
> >   #define IOV_MAX 1024
> >
> > in this same file
>
> Mmm, I wondered about that, although in that case it's
> "for when the host has no iov implementation at all
> and we're rolling our own".
>
> thanks
> -- PMM

I think that although the two cover different cases, in order for the
patch to be correct we should indeed remove the later duplication,
otherwise compilation will fail on systems lacking IOVEC. Thank you
both for the review