Re: [Xen-devel] [PATCH] enable QEMU for ARM builds

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 10 Jul 2014, Ian Campbell wrote:
> On Thu, 2014-07-10 at 15:04 +0100, Stefano Stabellini wrote:
> > On Thu, 10 Jul 2014, Ian Campbell wrote:
> > > On Thu, 2014-07-10 at 12:18 +0100, Stefano Stabellini wrote:
> > > > Build qemu-xen on ARM and ARM64: it is used to provide the PV backends,
> > > > disk and framebuffer in particular.
> > > > 
> > > > Ideally we would also modify the configure options to only build what is
> > > > necessary: a machine just for PV backends. However that is a work in
> > > > progress and not yet available in QEMU (see
> > > > http://marc.info/?l=qemu-devel&m=139082425718379&w=2). So we just build
> > > > the usual i386 target, even though no i386 emulation is going to be done
> > > > by qemu-xen on ARM.
> > > 
> > > As I mentioned IRL we need to confirm that this doesn't end up exposing
> > > a protocol property in the xenstore backend dir of
> > > XEN_IO_PROTO_ABI_X86_* instead of XEN_IO_PROTO_ABI_ARM.
> > 
> > QEMU doesn't write the protocol to xenstore. In fact the protocol is
> > written to xenstore by the frontend so this shouldn't be a problem. 
> 
> Oh good, I was misremembering which way round it was.
> 
> > > Likewise we need to be sure that the code actually implements the ARM
> > > protocol, not one of the x86 ones.
> > 
> > Sure. No matter the QEMU target architecture,  qdisk and xenfb implement
> > NATIVE as well as x86 protocols.
> 
> When built as an ARM binary with x86 as the target architecture what
> does it consider to be the NATIVE protocol?

ARM

 
> You didn't mention the ARM protocol, hopefully just an oversight?

NATIVE is defined as ARM when building on arm:

xen/include/public/io/protocols.h

and because aarch64 and arm use the same protocol qemu don't need to
special case them.

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