Re: [fixed-PATCH] cmpxchg(8b).

["Paweł Sikora" <pluto@pld-linux.org>]

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--- linux-2.6.8-rc3/arch/i386/Kconfig.orig	2004-08-07 07:52:57.000000000 +0200
+++ linux-2.6.8-rc3/arch/i386/Kconfig	2004-08-07 10:37:33.204220304 +0200
@@ -342,6 +342,11 @@
 	depends on !M386
 	default y
 
+config X86_CMPXCHG8B
+	bool
+	depends on !M386 && !M486
+	default y
+
 config X86_XADD
 	bool
 	depends on !M386
--- linux-2.6.8-rc3/arch/x86_64/Kconfig.orig	2004-08-07 14:22:20.000000000 +0200
+++ linux-2.6.8-rc3/arch/x86_64/Kconfig	2004-08-07 14:42:35.503414192 +0200
@@ -45,6 +45,10 @@
 	bool
 	default y
 
+config X86_CMPXCHG8B
+	bool
+	default y
+
 config EARLY_PRINTK
 	bool
 	default y
--- linux-2.6.8-rc3/drivers/acpi/Kconfig.orig	2004-08-03 23:28:51.000000000 +0200
+++ linux-2.6.8-rc3/drivers/acpi/Kconfig	2004-08-07 14:45:14.718209864 +0200
@@ -5,11 +5,11 @@
 menu "ACPI (Advanced Configuration and Power Interface) Support"
 	depends on !X86_VISWS
 	depends on !IA64_HP_SIM
-	depends on IA64 || X86
+	depends on IA64 || X86_CMPXCHG
 
 config ACPI
 	bool "ACPI Support"
-	depends on IA64 || X86
+	depends on IA64 || X86_CMPXCHG
 
 	default y
 	---help---
--- linux-2.6.8-rc3/drivers/char/drm/Kconfig.orig	2004-08-03 23:28:30.000000000 +0200
+++ linux-2.6.8-rc3/drivers/char/drm/Kconfig	2004-08-07 12:49:55.413820920 +0200
@@ -6,6 +6,7 @@
 #
 config DRM
 	bool "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
+	depends on !X86 || X86_CMPXCHG
 	help
 	  Kernel-level support for the Direct Rendering Infrastructure (DRI)
 	  introduced in XFree86 4.0. If you say Y here, you need to select
--- linux-2.6.8-rc3/include/asm-i386/fixmap.h.orig	2004-08-03 23:26:45.000000000 +0200
+++ linux-2.6.8-rc3/include/asm-i386/fixmap.h	2004-08-07 23:59:39.076427856 +0200
@@ -15,7 +15,9 @@
 
 #include <linux/config.h>
 #include <linux/kernel.h>
+#ifdef CONFIG_ACPI_BOOT
 #include <asm/acpi.h>
+#endif
 #include <asm/apicdef.h>
 #include <asm/page.h>
 #ifdef CONFIG_HIGHMEM
--- linux-2.6.8-rc3/include/asm-i386/system.h.orig	2004-08-08 01:56:24.000000000 +0200
+++ linux-2.6.8-rc3/include/asm-i386/system.h	2004-08-08 01:58:18.543104408 +0200
@@ -149,8 +149,14 @@
 #define __xg(x) ((struct __xchg_dummy *)(x))
 
 
+#ifdef CONFIG_X86_CMPXCHG8B
+#define __HAVE_ARCH_CMPXCHG8B 1
+
 /*
- * The semantics of XCHGCMP8B are a bit strange, this is why
+ * CMPXCHG8B isn't supported on Intel processors earlier
+ * than the Pentium processors.
+ *
+ * The semantics of CMPXCHG8B are a bit strange, this is why
  * there is a loop and the loading of %%eax and %%edx has to
  * be inside. This inlines well in most cases, the cached
  * cost is around ~38 cycles. (in the future we might want
@@ -163,8 +169,9 @@
  * of the instruction set reference 24319102.pdf. We need
  * the reader side to see the coherent 64bit value.
  */
-static inline void __set_64bit (unsigned long long * ptr,
-		unsigned int low, unsigned int high)
+static __inline__ void __set_64bit(unsigned long long * ptr,
+				    const unsigned int low,
+				    const unsigned int high)
 {
 	__asm__ __volatile__ (
 		"\n1:\t"
@@ -179,29 +186,19 @@
 		:	"ax","dx","memory");
 }
 
-static inline void __set_64bit_constant (unsigned long long *ptr,
-						 unsigned long long value)
-{
-	__set_64bit(ptr,(unsigned int)(value), (unsigned int)((value)>>32ULL));
-}
-#define ll_low(x)	*(((unsigned int*)&(x))+0)
-#define ll_high(x)	*(((unsigned int*)&(x))+1)
-
-static inline void __set_64bit_var (unsigned long long *ptr,
-			 unsigned long long value)
-{
-	__set_64bit(ptr,ll_low(value), ll_high(value));
-}
+#define set_64bit(ptr, value) 						\
+	(__builtin_constant_p(value) ? 					\
+	    __set_64bit(ptr,						\
+			    (const unsigned int)(value),		\
+			    (const unsigned int)((value) >> 32ULL)	\
+			) :						\
+	    __set_64bit(ptr,						\
+			    *(((const unsigned int *)&(value)) + 0),	\
+			    *(((const unsigned int *)&(value)) + 1)	\
+			)						\
+	)
 
-#define set_64bit(ptr,value) \
-(__builtin_constant_p(value) ? \
- __set_64bit_constant(ptr, value) : \
- __set_64bit_var(ptr, value) )
-
-#define _set_64bit(ptr,value) \
-(__builtin_constant_p(value) ? \
- __set_64bit(ptr, (unsigned int)(value), (unsigned int)((value)>>32ULL) ) : \
- __set_64bit(ptr, ll_low(value), ll_high(value)) )
+#endif
 
 /*
  * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
@@ -233,18 +230,21 @@
 	return x;
 }
 
+#ifdef CONFIG_X86_CMPXCHG
+#define __HAVE_ARCH_CMPXCHG 1
+
 /*
  * Atomic compare and exchange.  Compare OLD with MEM, if identical,
  * store NEW in MEM.  Return the initial value in MEM.  Success is
  * indicated by comparing RETURN with OLD.
+ *
+ * CMPXCHG isn't supported on Intel processors earlier than
+ * the Intel486 processors.
  */
-
-#ifdef CONFIG_X86_CMPXCHG
-#define __HAVE_ARCH_CMPXCHG 1
-#endif
-
-static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
-				      unsigned long new, int size)
+static __inline__ unsigned long __cmpxchg(volatile void *ptr,
+			    		    const unsigned long old,
+					    const unsigned long new,
+					    const int size)
 {
 	unsigned long prev;
 	switch (size) {
@@ -270,10 +270,14 @@
 	return old;
 }
 
-#define cmpxchg(ptr,o,n)\
-	((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
-					(unsigned long)(n),sizeof(*(ptr))))
-    
+#define cmpxchg(ptr, o, n)					\
+	((__typeof__(*(ptr)))__cmpxchg((ptr),			\
+					(unsigned long)(o),	\
+					(unsigned long)(n),	\
+					sizeof(*(ptr))))
+
+#endif
+
 #ifdef __KERNEL__
 struct alt_instr { 
 	__u8 *instr; 		/* original instruction */