Re: [Qemu-devel] Qemu baseline requirements/portability?

[Daniel P . Berrangé]

On Thu, Jun 06, 2019 at 07:30:08AM +0200, Markus Armbruster wrote:
> "H. Peter Anvin" <address@hidden> writes:
> 
> > On 6/5/19 12:55 PM, H. Peter Anvin wrote:
> >> Hi,
> >> 
> >> I am writing some code I'm hoping will be able to make it into Qemu, but I
> >> can't seem to find what the baseline portability requirements are.  I'm
> >> specifically wondering about newer POSIX features like openat(), which 
> >> seems
> >> to be used in the 9p filesystem and nowhere else, and what version of glib 
> >> one
> >> can rely on?
> >> 
> >
> > Specifically, I'm trying to satisfy a 10-year-old request by me and others 
> > to
> > support composite initrd during Linux boot.
> 
> Please peruse qemu-doc.texi @appendix Supported build platforms.  If it
> doesn't fully answer your question, ask for clarification here.

And specificially on the glib version question, we currently mandate 2.40.

If you try to use a glib API from a version newer than 2.40 we have things
setup so that you should get a fatal compile error due to our use of

   #define GLIB_VERSION_MAX_ALLOWED GLIB_VERSION_2_40


If you do think it is useful to have an API from glib > 2.40 you can put
some back compat logic in include/glib-compat.h so that you can use the
newer API and gracefully degrade on older glib.

Regards,
Daniel
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