From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Daniel P. Berrange" Subject: Memory barrier definitions in xenctrl.h for ia64? Date: Mon, 18 Sep 2006 19:07:53 +0100 Message-ID: <20060918180753.GG25730@redhat.com> Reply-To: "Daniel P. Berrange" Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Looking in tools/libxc/xenctrl.h it seems we define macros for memory barriers, #if defined(__i386__) #define mb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" ) #define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" ) #define wmb() __asm__ __volatile__ ( "" : : : "memory") #elif defined(__x86_64__) #define mb() __asm__ __volatile__ ( "mfence" : : : "memory") #define rmb() __asm__ __volatile__ ( "lfence" : : : "memory") #define wmb() __asm__ __volatile__ ( "" : : : "memory") #elif defined(__ia64__) /* FIXME */ #define mb() #define rmb() #define wmb() #elif defined(__powerpc__) /* XXX loosen these up later */ #define mb() __asm__ __volatile__ ("sync" : : : "memory") #define rmb() __asm__ __volatile__ ("sync" : : : "memory") /* lwsync? */ #define wmb() __asm__ __volatile__ ("sync" : : : "memory") /* eieio? */ #else #error "Define barriers" #endif I'm not familiar with ia64 myself - does it really not need memory barriers? The userspace tools blktap, xenfb & xconsoled are all using these macros in various places so if ia64 does indeed need memory barriers it looks like there is some nasty bug potential here Regards, Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|