[Xen-devel] Suggested changes to xen/include from recent Linux

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

As I mentioned at the xummit (spelling intended :-), a
Xen/ia64 contributor from SGI (Greg Edwards) is updating
the Xen/ia64 Linux dependencies from 2.6.7 to 2.6.11.
This is now working, but he identified a couple places
where it would make sense to modify common (include/xen)
files.  So, rather than just "fix" them in ia64-specific
files, I thought I would publish them for comment and to
see if they might/should go into include/xen:

1) In include/xen/spinlock.h:

Linux has started using the following define:

#define DEFINE_SPINLOCK(x) spinlock_t x = SPIN_LOCK_UNLOCKED

I see that the construct could be used throughout xen/arch/x86
as well... indeed there are TWO C files where a similar macro
is defined but called DECLARE_MUTEX.

I propose adding the macro.

2) In include/xen/types.h:

Starting in 2.6.9, there are some new type-checking attributes and
the following lines have been added to include/linux/types.h.  There's
some explanation of it here:

http://kerneltrap.org/node/3848  (search for __bitwise)

Since Jimi mentioned a need for bi-endian support in Xen/ppc, I thought
these might be added eventually anyway, so they could be added now
to include/xen/type.s.

I propose adding the lines (possibly including the comment verbatim?)

/*
 * Below are truly Linux-specific types that should never collide with
 * any application/library that wants linux/types.h.
 */

#ifdef __CHECKER__
#define __bitwise __attribute__((bitwise))
#else
#define __bitwise
#endif

typedef __u16 __bitwise __le16;
typedef __u16 __bitwise __be16;
typedef __u32 __bitwise __le32;
typedef __u32 __bitwise __be32;
#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
typedef __u64 __bitwise __le64;
typedef __u64 __bitwise __be64;
#endif

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