| Message ID | 1393451610-24617-1-git-send-email-peter.maydell@linaro.org |
|---|---|
| State | Accepted |
| Commit | 4c288acbd6b9eccb13076103e59a426af3d15030 |
| Headers | show |
On 02/26/2014 01:53 PM, Peter Maydell wrote: > In QEMU we don't make any use at all of the common symbol > functionality, so we can avoid this problem entirely simply > by compiling with -fno-common. Enable this option for all > builds, not just MacOSX, so that if we ever inadvertently > introduce multiple definitions of some variable that will > be immediately spotted as a build error rather than only > breaking the MacOSX build. > > Suggested-by: Markus Armbruster <armbru@redhat.com> > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net> r~
On 28 February 2014 17:19, Richard Henderson <rth@twiddle.net> wrote: > On 02/26/2014 01:53 PM, Peter Maydell wrote: >> In QEMU we don't make any use at all of the common symbol >> functionality, so we can avoid this problem entirely simply >> by compiling with -fno-common. Enable this option for all >> builds, not just MacOSX, so that if we ever inadvertently >> introduce multiple definitions of some variable that will >> be immediately spotted as a build error rather than only >> breaking the MacOSX build. >> >> Suggested-by: Markus Armbruster <armbru@redhat.com> >> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> > > Reviewed-by: Richard Henderson <rth@twiddle.net> Thanks. Applied to master as a MacOSX buildfix. -- PMM
diff --git a/configure b/configure index 423f435..ff438e4 100755 --- a/configure +++ b/configure @@ -369,7 +369,7 @@ sdl_config="${SDL_CONFIG-${cross_prefix}sdl-config}" ARFLAGS="${ARFLAGS-rv}" # default flags for all hosts -QEMU_CFLAGS="-fno-strict-aliasing $QEMU_CFLAGS" +QEMU_CFLAGS="-fno-strict-aliasing -fno-common $QEMU_CFLAGS" QEMU_CFLAGS="-Wall -Wundef -Wwrite-strings -Wmissing-prototypes $QEMU_CFLAGS" QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls $QEMU_CFLAGS" QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $QEMU_CFLAGS"
MacOSX doesn't pull .o files from .a archives if the symbol that it requires is one which the .o file defines as a common symbol. (Common symbols are those declared without "extern"; the linker will merge together common symbols with the same name, so redeclaring the same variable in two compilation units results in them referring to the same symbol rather than a compilation error). This MacOSX difference from traditional linker behaviour means that "make check" produces link errors: Undefined symbols for architecture x86_64: "_cur_mon", referenced from: _error_vprintf in libqemuutil.a(qemu-error.o) _error_printf in libqemuutil.a(qemu-error.o) _error_printf_unless_qmp in libqemuutil.a(qemu-error.o) _error_print_loc in libqemuutil.a(qemu-error.o) _error_report in libqemuutil.a(qemu-error.o) ld: symbol(s) not found for architecture x86_64 in this case because "cur_mon" is a common symbol in libqemustub.a(mon-set-error.o). In QEMU we don't make any use at all of the common symbol functionality, so we can avoid this problem entirely simply by compiling with -fno-common. Enable this option for all builds, not just MacOSX, so that if we ever inadvertently introduce multiple definitions of some variable that will be immediately spotted as a build error rather than only breaking the MacOSX build. Suggested-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- Thanks to Markus for pointing out that -fno-common was the simple solution to this problem. make check now works on MacOSX, although due to a race condition in the version of glib I'm stuck on (2.22.4) I have to periodically use "killall -CHLD gtester" to unwedge it... configure | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)