Re: [Xen-devel] [PATCH 1/4] interface: avoid redefinition of __XEN_INTERFACE_VERSION__

[Juergen Gross <jgross@xxxxxxxx>]

On 28/02/17 12:11, Jan Beulich wrote:
>>>> On 28.02.17 at 11:34, <JGross@xxxxxxxx> wrote:
>> In stubdom environment __XEN_INTERFACE_VERSION__ is sometimes defined
>> on the command line of the build instruction. This conflicts with
>> xen-compat.h defining it unconditionally if __XEN__ or __XEN_TOOLS__
>> is set.
> 
> Then that's what wants fixing. In fact it's questionable whether
> __XEN_TOOLS__ (or even __XEN__) getting defined there is
> appropriate.

There are multiple libraries from the tools directory being compiled
for stubdoms.

>> Just use #undef in this case to avoid the resulting warning.
> 
> I think the lack of a warning in case of a collision is worse here.
> People should simply not define both the version symbol and
> either of __XEN__ or __XEN_TOOLS__.

Would you be okay with:

#if defined(__XEN_INTERFACE_VERSION__)
  #if __XEN_INTERFACE_VERSION__ != __XEN_LATEST_INTERFACE_VERSION__
    #error ...
  #endif
#else
  #define __XEN_INTERFACE_VERSION__ __XEN_LATEST_INTERFACE_VERSION__
#endif


Juergen

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