[Qemu-devel] Qemu baseline requirements/portability?

[Qemu-devel] Qemu baseline requirements/portability?

[H. Peter Anvin]

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?

Thanks,

	-hpa

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

[H. Peter Anvin]

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.

	-hpa

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

[Markus Armbruster]

"H. Peter Anvin" <hpa@zytor.com> 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.

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" <hpa@zytor.com> 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
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|