Re: [Qemu-devel] [PATCH RFC 0/5] Xen: introduce Xen PV target

[Paolo Bonzini]

Il 23/01/2014 23:30, Peter Maydell ha scritto:
> > > As promised I hacked a prototype based on Paolo's disable TCG series.
> > > However I coded some stubs for TCG anyway. So this series in principle
> > > should work with / without Paolo's series.
> I'm afraid I still think this is a terrible idea. "Xen" isn't a CPU, and
> "the binary is smaller" isn't IMHO sufficient justification for breaking
> QEMU's basic structure of "target-* define target CPUs and we have
> a lot of compile time constants which are specific to a CPU which
> get defined there". How would you support a bigendian Xen CPU,
> just to pick one example of where this falls down?

(1) decide that the Xen ring buffers are little-endian even on 
big-endian CPUs

(2) communicate the endianness of the Xen ring buffers via Xenstore, 
just like we do for sizeof(long), and let the guest use either 
endianness on any architecture.

Paolo