Re: [Xen-devel] [PATCH] xen: use vMSI related #define-s from public interface

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.09.17 at 11:23, <roger.pau@xxxxxxxxxx> wrote:
> On Mon, Sep 04, 2017 at 03:04:41AM -0600, Jan Beulich wrote:
>> >>> On 01.09.17 at 20:20, <roger.pau@xxxxxxxxxx> wrote:
>> > On Fri, Sep 01, 2017 at 10:25:42AM -0600, Jan Beulich wrote:
>> >> Xen and qemu having identical #define-s (with different names) is a
>> >> strong hint that these should have been part of the public interface
>> >> from the very start. Use them if they're available, falling back to
>> >> privately defined values only when using older headers.
>> >> 
>> >> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>> > 
>> > Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>> 
>> Thanks.
>> 
>> >> --- a/hw/xen/xen_pt_msi.c
>> >> +++ b/hw/xen/xen_pt_msi.c
>> >> @@ -18,6 +18,11 @@
>> >>  
>> >>  #define XEN_PT_AUTO_ASSIGN -1
>> >>  
>> >> +#ifndef XEN_DOMCTL_VMSI_X86_DEST_ID_MASK
>> >> +#if XEN_DOMCTL_INTERFACE_VERSION >= 0x0000000e
>> > 
>> > XEN_DOMCTL_INTERFACE_VERSION is already 0xe (without you added
>> > defines), I guess it doesn't matter much because we only care for
>> > stable releases.
>> 
>> Well, that's if you build qemu against master Xen. What about
>> people building against older Xen versions/headers?
> 
> Sorry, I think I haven't explained myself clearly. What I mean is
> that if this change gets committed before the Xen side one, QEMU would
> not compile against current Xen. As said, this is only a transitory
> issue, and it's never going to be a problem in stable branches. This
> is because of the "#error" that you add.

Oh, yes, that's the case. I can't see an easy way around it, but I'm
pretty sure the qemu side of it will see some further delay anyway.

Jan

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