[Xen-devel] question regarding gnu-isms

[Aron Griffis <aron@xxxxxx>]

I understand most of the gcc extensions that I find in xen, for
example ({...}) in a #define.  However I've come across a couple that
I'm not familiar with.  Does somebody mind explaining the point of
these?

from linux-2.6-xen-sparse/include/asm-ia64/hypervisor.h:

    #define __pte_ma(_x)    ((pte_t) {(_x)})

    What's the point of the braces here?

same file:

    #define xen_create_contiguous_region(vstart, order, address_bits) ({0;})

    This looks like the usual ({...}) construction but seems
    pointless.  The nearest explanation I could gather for this
    applies only to C++...  surely I'm missing something. :-)

Thanks,
Aron

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