[PATCH] cpu barriers moved and x86-64 barriers add

[Jerone Young <jyoung5@us.ibm.com>]

[-- Attachment #1: Type: text/plain, Size: 1521 bytes --]

We actually should have wmb() be defined as "asm volatile("":::"memory")
since we are not using out of order io.

The patch attached removes all the instances and places the definitions
in libxc/xc.h as per the discussion last week between Anthony & Keir.


Signed-off-by: Jerone Young <jyoung5@us.ibm.com>


On Tue, 2005-03-01 at 15:23 -0600, Anthony Liguori wrote:
> Keir Fraser wrote:
> 
> >
> > On 1 Mar 2005, at 19:56, Jerone Young wrote:
> >
> >>     I would like to discuss is this correct, dead wrong, or even 
> >> needed at
> >> all?
> >
> >
> > x86/64 has proper barrier instructions -- see 
> > include/asm-x86_64/system.h in Linux. It is from there that we should 
> > pull our definitions. Barrier macros are defined in a few places in 
> > the tools -- we ought to pull them all into one single header 
> > incorporated by all tools that need it.
> 
> I was just about to send this out myself :-)  I think the consensus was 
> to put them all in xc.h.  I posted a patch recently that made everything 
> include asm/system.h.  All it should take is replacing asm/system.h with 
> xc.h in the patch and then making the necessary changes to xc.h.
> 
> For reference, the proper x86-64 barriers are:
> 
> #define mb()     asm volatile("mfence":::"memory")
> #define rmb()    asm volatile("lfence":::"memory")
> #define wmb()    asm volatile("sfence":::"memory")
> 
> Regards,
> Anthony Liguori
> 
-- 
Jerone Young
Open Virtualization
IBM Linux Technology Center
jyoung5@us.ibm.com
512-838-1157 (T/L: 678-1157)

[-- Attachment #2: cpu_barrier_patch.diff --]
[-- Type: text/x-patch, Size: 3223 bytes --]

diff -Nur xen-unstable-0301.orig/tools/blktap/blktaplib.h xen-unstable-0301-test/tools/blktap/blktaplib.h
--- xen-unstable-0301.orig/tools/blktap/blktaplib.h	2005-03-01 06:54:49.000000000 -0600
+++ xen-unstable-0301-test/tools/blktap/blktaplib.h	2005-03-01 16:24:25.780124280 -0600
@@ -10,22 +10,6 @@
 
 #include <stdint.h>
 
-typedef uint8_t            u8;
-typedef uint16_t           u16;
-typedef uint32_t           u32;
-typedef uint64_t           u64;
-typedef int8_t             s8;
-typedef int16_t            s16;
-typedef int32_t            s32;
-typedef int64_t            s64;
-                                                                                
-#if defined(__i386__)
-#define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define wmb() __asm__ __volatile__ ( "" : : : "memory" )
-#else
-#error "Define barriers"
-#endif
-    
 #include <sys/user.h>
 #include <xen/xen.h>
 #include <xen/io/blkif.h>
diff -Nur xen-unstable-0301.orig/tools/libxc/xc.h xen-unstable-0301-test/tools/libxc/xc.h
--- xen-unstable-0301.orig/tools/libxc/xc.h	2005-03-01 06:54:49.000000000 -0600
+++ xen-unstable-0301-test/tools/libxc/xc.h	2005-03-01 16:05:53.248254832 -0600
@@ -25,6 +25,21 @@
 #include <xen/event_channel.h>
 #include <xen/sched_ctl.h>
 
+
+/*\
+ *  DEFINITIONS FOR CPU BARRIERS
+\*/ 
+#if defined(__i386__)
+#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")
+#else
+#error "Define barriers"
+#endif
+
 /*\
  *  INITIALIZATION FUNCTIONS
 \*/ 
diff -Nur xen-unstable-0301.orig/tools/python/xen/lowlevel/xu/xu.c xen-unstable-0301-test/tools/python/xen/lowlevel/xu/xu.c
--- xen-unstable-0301.orig/tools/python/xen/lowlevel/xu/xu.c	2005-03-01 06:54:49.000000000 -0600
+++ xen-unstable-0301-test/tools/python/xen/lowlevel/xu/xu.c	2005-03-01 16:01:13.083846296 -0600
@@ -49,14 +49,6 @@
 /* Size of a machine page frame. */
 #define PAGE_SIZE 4096
 
-#if defined(__i386__)
-#define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define wmb() __asm__ __volatile__ ( "" : : : "memory" )
-#else
-#error "Define barriers"
-#endif
-
-
 /* Set the close-on-exec flag on a file descriptor.  Doesn't currently bother
  * to check for errors. */
 /*
diff -Nur xen-unstable-0301.orig/tools/xcs/xcs.h xen-unstable-0301-test/tools/xcs/xcs.h
--- xen-unstable-0301.orig/tools/xcs/xcs.h	2005-03-01 06:54:49.000000000 -0600
+++ xen-unstable-0301-test/tools/xcs/xcs.h	2005-03-01 16:02:22.707261928 -0600
@@ -39,13 +39,6 @@
 /* Size of a machine page frame. */
 #define PAGE_SIZE 4096
 
-#if defined(__i386__)
-#define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define wmb() __asm__ __volatile__ ( "" : : : "memory" )
-#else
-#error "Define barriers"
-#endif
-
 #ifndef timersub /* XOPEN and __BSD don't cooperate well... */
 #define timersub(a, b, result)                                                \
   do {                                                                        \