Re: Cross-compilation artifact is broken

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Mar 12, 2025 at 02:05:09PM +0000, Daniel P. Berrangé wrote:
> On Wed, Mar 12, 2025 at 03:52:45PM +0200, Konstantin Kostiuk wrote:
> > Hi All,
> > 
> > I cross-compiled qemu-ga from current master branch
> > (825b96dbcee23d134b691fc75618b59c5f53da32) and found strange behavior.
> > 
> > Configure CLI:
> > ./configure --disable-docs --disable-system --disable-user
> > --cross-prefix=x86_64-w64-mingw32- --enable-guest-agent
> > --disable-guest-agent-msi --disable-qga-vss
> > Build CLI:
> > make -j8 qemu-ga
> > 
> > Linker wrote the following information but exited with 0 code:
> > 
> > /usr/lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld:
> > qga/qemu-ga.exe:/4: section below image base
> > /usr/lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld:
> > qga/qemu-ga.exe:/24: section below image base
> > 
> > As a result, this binary failed to start on Windows without any details,
> > just a message that the application is not compatible. I also tried to run
> > it with wine and got the error:
> > 
> > wine: failed to start
> > L"Z:\\home\\user\\Documents\\repos\\qemu\\build\\qga\\qemu-ga.exe"
> > Application could not be started, or no application associated with the
> > specified file.
> > ShellExecuteEx failed: Bad EXE format for
> > Z:\home\user\Documents\repos\qemu\build\qga\qemu-ga.exe.
> > 
> > I bisected the tree and found the commit that caused the problem:
> > https://gitlab.com/qemu-project/qemu/-/commit/563b1a35ed1f1151505d4fe5f723827d1b3fd4bc
> > 
> > Adding --disable-split-debug to the configure CLI fixes the issue.
> > 
> > $ x86_64-w64-mingw32-gcc --version
> > x86_64-w64-mingw32-gcc (GCC) 14.2.0
> > 
> > My question is, is this expected behavior or is this a bug?
> 
> Your configure args don't include "--enable-debug", so I would
> not have expected -gsplit-dwarf to have been enabled, so I'm
> surprised that commit casued a problem.

Hmm it appears that the meson  "get_option('debug')" is entirely
unconnected to QEMU's --enable-debug configure flag, which I did
not realize.

IOW, we've got -gsplit-dwarf enabled by default for everyone
building QEMU, which feels dubious. IMHO only an explicit
--enable-debug configure arg should have triggered it.

In addition since its breaking Windows builds, it appears we
need to block its usage on Windows.


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 :|