On Thu, Oct 13, 2022 at 11:39:34AM +0100, Peter Maydell wrote: > On Thu, 13 Oct 2022 at 09:47, Michal Privoznik <mpriv...@redhat.com> wrote: > > > > When determining the endiandness of the target architecture we're > > building for a small program is compiled, which in an obfuscated > > way declares two strings. Then, we look which string is in > > correct order (using strings binary) and deduct the endiandness. > > But using the strings binary is problematic, because it's part of > > toolchain (strings is just a symlink to > > x86_64-pc-linux-gnu-strings or llvm-strings). And when > > (cross-)compiling, it requires users to set the symlink to the > > correct toolchain. > > > > Fortunately, we have a better alternative anyways. Since we > > require either clang or gcc we can rely on macros they declare. > > > > Bug: https://bugs.gentoo.org/876933 > > Signed-off-by: Michal Privoznik <mpriv...@redhat.com> > > If we can determine this just by looking at C macros, does > this really need to be a configure test at all ? Paolo?
We don't need to rely on CLang / GCC macros either, as this is exposed by GLib $ grep BYTE_ORDER /usr/lib64/glib-2.0/include/glibconfig.h #define G_BYTE_ORDER G_LITTLE_ENDIAN IOW, any code that needs to know can do one of: #if G_BYTE_ORDER == G_LITTLE_ENDIAN #if G_BYTE_ORDER == G_BIG_ENDIAN The only thing 'configure' seems to be doing with the 'bigendian' env var it sets, is to construct a meson cross compiler spec if test "$cross_compile" = "yes"; then cross_arg="--cross-file config-meson.cross" echo "[host_machine]" >> $cross echo "system = '$targetos'" >> $cross case "$cpu" in i386) echo "cpu_family = 'x86'" >> $cross ;; *) echo "cpu_family = '$cpu'" >> $cross ;; esac echo "cpu = '$cpu'" >> $cross if test "$bigendian" = "yes" ; then echo "endian = 'big'" >> $cross else echo "endian = 'little'" >> $cross fi so we do need a compile time test in configure, but I'd suggest using G_BYTE_ORDER With 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 :|