Re: [Qemu-devel] [PATCH] configure: use glib in glib pkg-config check.

[Peter Maydell]

On 3 February 2014 22:56, Chris Johns <address@hidden> wrote:
> On 3/02/2014 9:29 pm, Daniel P. Berrange wrote:
>> This change will cause  -pthread linker + compiler flag to be lost.
>>
>
> I see in gthread-2.0.pc ..
>
>  Libs: -L${libdir} -lgthread-2.0
>  Cflags: -D_REENTRANT
>
> and qemu includes 'glib.h'. Without the glib pc flags being used the build
> fails not being able to find 'glib.h'.
>
> I have no idea about the relationship this has with -pthread. Are both
> needed ? It is not a problem on darwin.

If you're going to make changes to configure it would be wiser to test
them also on Linux. Darwin is a bit of an outlier as far as QEMU goes.

In particular, the reason you're not noticing a problem:

manooth$ pkg-config --cflags gthread-2.0
-I/sw/include/glib-2.0 -I/sw/lib/glib-2.0/include

because on MacOSX we don't need any special flags for threading.
However on Linux it's the gthread-2.0 cflags that add -pthread:

address@hidden:/tmp$ pkg-config --cflags gthread-2.0
-pthread -I/usr/include/glib-2.0 -I/usr/lib/i386-linux-gnu/glib-2.0/include

because we do need special flags, and you've just dropped those.

Incidentally, on my Mountain Lion system:

manooth$ pkg-config --cflags glib-2.0
-I/sw/include/glib-2.0 -I/sw/lib/glib-2.0/include

and you can see that both gthread-2.0 and glib-2.0 give the same
set of includes.

(that's some random glib, I think 2.0.25, from fink packages.)

>> What glib version are you seeing a problem with ?
>
>
> glib-2.39.3 on darwin 13.0.2 (Mavrick).

Do Apple provide that with the system these days, or have you
installed that from some third-party (if so, who?)

Anyway, I notice from the glib documentation that the docs for
glib 2.30:
https://developer.gnome.org/glib/2.30/glib-compiling.html
talk about using pkg-config gthread-2.0, but the docs for 2.32
and later:
https://developer.gnome.org/glib/2.32/glib-compiling.html
don't any more. Is this the glib devs inflicting random churn
on everybody's build scripts?

Do you get the same version number from
'pkg-config --version gthread-2.0' as you do from
'pkg-config --version glib-2.0' or is the gthread pkg info
you have an old stale version, maybe?

thanks
-- PMM