Re: [Xen-devel] [PATCH] qemu build: disable C++ optional code

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 7 Jul 2014, Ian Campbell wrote:
> On Mon, 2014-07-07 at 12:47 +0100, Stefano Stabellini wrote:
> > Disable C++ optimizations for the intruction emulators: we don't need
> > them and they can cause build issues with Xen.
> 
> This doesn't help distros who want to use their existing qemu packages
> with Xen though, or in general people who prefer their own qemu to ours.

That is true, however if you are going to compile QEMU to use it as Xen
device model and nothing else, you might as well disable things you
don't need, such KVM support and C++ optimization.
That's why I sent the patch.


> What sort of build issues do we see? Is this to do with
> xen/include/public not being C++ safe or is it code issues within the
> Xen parts or qemu?

The problem is that we use --extra-cflags to pass

-I$(XEN_ROOT)/tools/include
-I$(XEN_ROOT)/tools/libxc
-I$(XEN_ROOT)/tools/xenstore

tools/utils contains an header file named utils.h, same name as
disas/libvixl/utils.h in QEMU. Files under disas/libvixl #include
"utils.h" picking up the wrong one. For some reason, I have only seen
this build problem on ARM so far.



> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > 
> > 
> > diff --git a/tools/Makefile b/tools/Makefile
> > index f4aa200..da20f5a 100644
> > --- a/tools/Makefile
> > +++ b/tools/Makefile
> > @@ -201,6 +201,7 @@ subdir-all-qemu-xen-dir: qemu-xen-dir-find
> >             --disable-kvm \
> >             --disable-docs \
> >             --disable-guest-agent \
> > +           --cxx=none \
> >             --python=$(PYTHON) \
> >             $(CONFIG_QEMUU_EXTRA_ARGS) \
> >             $(IOEMU_CONFIGURE_CROSS); \
> 
> 

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