I was running a series of tests on 32 and 64 bit hosts to test for
endianness and variable width issues when I noticed that I couldn't
properly perform a build of "make check" against a 32bit target from a
64bit host:
../../configure --cpu=i386 && make -j4 && make check
This produces some warnings in tests-cutils about overflowing variables
that are of type guint64. It's been mentioned on the mailing lists
before, actually:
http://lists.gnu.org/archive/html/qemu-devel/2014-05/msg00452.html
The problem is that guint64 is being aliased against "unsigned long",
which is only 4 bytes instead of the implied 8. This occurs because we
link against the 64bit headers for glib instead of the 32bit ones when
we're building for i386 from an x86_64 host.
Our include flags wind up looking like: -I/usr/include/glib-2.0 but
-I/usr/lib64/glib-2.0/include
I was discussing the problem with Stefan:
On 08/21/2014 05:03 AM, Stefan Hajnoczi wrote:
The problem is that pkg-config uses libdir=/usr/lib64 by default on
amd64 hosts. It doesn't know that gcc -m32 is being used.
This results in glib's 64-bit headers being used where guint64 is just
unsigned long. On 32-bit hosts this is incorrect.
Two workarounds:
1. yum install pkgconfig.i686 and run it instead of pkgconfig.x86_64
2. Use the pkg-config --define-variable libdir=/usr/lib option
You can set PKG_CONFIG=path/to/pkg-config.i686 on QEMU's ./configure
command-line.
This is all distro-specific :(. Any other solutions?
Stefan
I am not extremely well versed in configure or pkg-config ninjutsu, but
I must imagine that the ARCH/cpu variables we are setting in configure
could help us know to call the 32bit pkg-config instead of the native
64bit version and fix this issue.
Does anyone have any good ideas? Surely other projects must have run
into this elsewhere.
--
—js