Xen devel - Feb 2010 - open-coded offsetof() in xen/include/public/ring.h

Using gcc 4.5 we''re seeing a build failure of the netfront driver due
to
its use of the __RING_SIZE() macro in the size specification of array
members of struct netfront_info. Since the use of pointer types in
integer constant expressions is an extension (albeit one - for the
specific form used here - so far supported by all compilers Xen
appears to be used with, and certainly all of the ones I was able to
test), I wonder whether requiring offsetof() to be defined in order
to use __RING_SIZE (or really a clone thereof usable in constant
expressions, since in that case a type rather than a pointer ought to
be passed in) would be acceptable.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

On 23/02/2010 14:07, "Jan Beulich" <JBeulich@novell.com> wrote:
> Using gcc 4.5 we''re seeing a build failure of the netfront driver
due to
> its use of the __RING_SIZE() macro in the size specification of array
> members of struct netfront_info. Since the use of pointer types in
> integer constant expressions is an extension (albeit one - for the
> specific form used here - so far supported by all compilers Xen
> appears to be used with, and certainly all of the ones I was able to
> test), I wonder whether requiring offsetof() to be defined in order
> to use __RING_SIZE (or really a clone thereof usable in constant
> expressions, since in that case a type rather than a pointer ought to
> be passed in) would be acceptable.
That would be acceptable. We already require some things like stdint types
to be pre-defined for example.

 -- Keir



_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel