patch-2.1.82 linux/arch/alpha/kernel/apecs.c

• Lines: 36
• Date: Sun Jan 25 10:35:16 1998
• Orig file: v2.1.81/linux/arch/alpha/kernel/apecs.c
• Orig date: Mon Jan 12 14:51:14 1998

diff -u --recursive --new-file v2.1.81/linux/arch/alpha/kernel/apecs.c linux/arch/alpha/kernel/apecs.c
@@ -18,6 +18,10 @@
 #include <asm/hwrpb.h>
 #include <asm/ptrace.h>
 
+/* NOTE: Herein are back-to-back mb insns.  They are magic. 
+   A plausible explanation is that the i/o controler does not properly
+   handle the system transaction.  Another involves timing.  Ho hum.  */
+
 extern struct hwrpb_struct *hwrpb;
 extern asmlinkage void wrmces(unsigned long mces);
 extern int alpha_sys_type;
@@ -162,6 +166,7 @@
 	/* access configuration space: */
 	value = *(vuip)addr;
 	mb();
+	mb();  /* magic */
 	if (apecs_mcheck_taken) {
 		apecs_mcheck_taken = 0;
 		value = 0xffffffffU;
@@ -242,6 +247,7 @@
 	/* access configuration space: */
 	*(vuip)addr = value;
 	mb();
+	mb();  /* magic */
 	apecs_mcheck_expected = 0;
 	mb();
 
@@ -539,7 +545,7 @@
 		apecs_mcheck_expected = 0;
 		apecs_mcheck_taken = 1;
 		mb();
-		mb();
+		mb(); /* magic */
 		apecs_pci_clr_err();
 		wrmces(0x7);
 		mb();