Re: [Qemu-devel] [PATCH 04/25] Add hard build dependency on glib

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> You're probably setting up your cross environment incorrectly which, 
> unfortunately, is very common.
> 
> The proper thing to do is to have GCC use a different system include 
> directory and a different prefix.  That will result in a directory where 
> there are gcc binaries with normal names installed in ${cross_prefix}/bin
> 
> You need to build and install pkg-config to this prefix too, and then 
> when it comes time to actually doing the QEMU configure, you should do 
> something like:
> 
> export PATH=${cross_prefix}/bin:$PATH
> export PKG_CONFIG_PATH=${cross_prefix}/lib/pkg-config:$PKG_CONFIG_PATH
> 
> Many automated cross compiler environment scripts will install specially 
> named versions of gcc and binutils in your normal $PATH.  The trouble 
> is, this is a bit of a hack and unless you know to make this hack work 
> with other build tools, it all comes tumbling down.

Well, that hard requirement is causing us problem on our 32/64-bit cross
builds as well.

It looks like glib (at least recent versions in -sid) can't be built
64-bit on a 32-bit system :-( At least not without fixing some horrid
bugs in there related to some generated include path from what David
says (I'll let him comment further).

In general, every time you add a library requirement without some config
option to disable it for cases such as ours, you add pain :-)

Now, in the specific case of glib, I understand why you would want to
get rid of re-invented wheels and use it, so I'm not specifically
criticizing that specific change, we'll eventually have to fix it
anyways. Just a heads up to be careful with hard requirements in
general.

Cheers,
Ben.