Re: [Qemu-devel] [PATCH v6] Add optionrom compatible with fw_cfg DMA version

[Richard W.M. Jones]

On Mon, May 09, 2016 at 04:31:26PM +0100, Stefan Hajnoczi wrote:
> On Mon, May 9, 2016 at 2:24 PM, Stefan Hajnoczi <address@hidden> wrote:
> > On Mon, Apr 25, 2016 at 05:04:40PM +0100, Richard W.M. Jones wrote:
> >> v5 -> v6:
> >>
> >>  - Changed the xen_load_linux assertion as suggested by Stefan.
> >>
> >>  - I renamed the variables in get_e801_addr function, since the
> >>    registers were really (16 bit 8086-style) AX, not EAX etc.  Also I
> >>    changed the GCC asm to make it a little bit more efficient.  I
> >>    verified by disassembling the function that GCC is still generating
> >>    the right code after this change.
> >>
> >>  - Re-tested with small (342K) libguestfs initramfs and with large
> >>    (20M) Fedora initramfs, and works fine in both cases.
> >
> > No one has picked this up, so I have (for QEMU 2.7).
> >
> > Thanks, applied to my block tree:
> > https://github.com/stefanha/qemu/commits/block
> 
> The bad news is this patch breaks the build under clang:
[...]
> The .code16gcc issue can probably be resolved with -m16 (which gcc
> 4.9+ also supports!).  I haven't looked into the other issues though.

It looks as if the easiest way to get around this will be to use
gas instead of clang's integrated assembler, ie:

  CFLAGS += -m16 -fno-integrated-as

However I have no idea if there are platforms we support which use
clang and require the integrated assembler instead of binutils.
Opinions on this?

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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