Re: [Qemu-devel] [PATCH v4] Add optionrom compatible with fw_cfg DMA version

[Stefan Hajnoczi]

On Tue, Feb 02, 2016 at 01:58:14PM +0100, Marc Marí wrote:
> El Tue, 02 Feb 2016 12:06:27 +0100
> Gerd Hoffmann <address@hidden> escribió:
> >   Hi,
> > 
> > >  %.img: %.o
> > > - $(call quiet-command,$(LD) $(LDFLAGS_NOPIE) -Ttext 0 -e
> > > _start -s -o $@ $<,"  Building $(TARGET_DIR)$@")
> > > + $(call quiet-command,$(LD) $(LDFLAGS_NOPIE) -m elf_i386
> > > -Ttext 0 -e _start -s -o $@ $<,"  Building $(TARGET_DIR)$@")
> > 
> > Hmm, that breaks the windows cross build:
> > 
> > make: Entering directory `/home/kraxel/projects/qemu/build-win32'
> >   Building optionrom/linuxboot_dma.img
> > i686-w64-mingw32-ld: unrecognised emulation mode: elf_i386
> > Supported emulations: i386pe
> > make[1]: *** [linuxboot_dma.img] Error 1
> 
> Thanks for reporting.
> 
> I don't know much about Windows cross-builds. Any idea on how to solve
> the issue?

The Windows toolchain doesn't use ELF binaries so -m elf_i386 doesn't
work there (the emulation is called "i386pe" in i686-w64-mingw32-ld).

I wonder whether it's possible to use gcc -m32 ... -o $@ %< as a wrapper
that automatically does the right thing.  But I guess it won't work
since gcc wants a C source file and not an object file as input.

You could make the emulation ("elf_i386" vs "i386pe") conditional on the
host platform (CONFIG_WIN32=y).

I'm not sure what the most elegant solution is.

Stefan

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