About Celeron processor memory barrier problem

From: michael chen <linux-kernel@vger.kernel.org>
To: alan@lxorguk.ukuu.org.uk, torvalds@transmeta.com
Cc: linux-kernel@vger.kernel.org
Subject: About Celeron processor memory barrier problem
Date: Thu, 23 Dec 1999 17:24:43 +0800	[thread overview]
Message-ID: <4015029078.19991223172443@turbolinux.com.cn> (raw)

Hi,
        I found that when I compiled the 2.4 kernel with the option
    of Pentium III or Pentium 4 on a Celeron's PC, it could cause  the
    system hang at very beginning boot stage, and I found the problem
    is cause by the fact that Intel Celeron doesn't have a real memory
    barrier,but when you choose the Pentium III option, the kernel
    assume the processor has a real memory barrier.
    Here is a patch to fix it:

    Merry Christmas :)
    Michael Chen

diff -Nur linux/include/asm-i386/system.h linux.new/include/asm-i386/system.h

--- linux/include/asm-i386/system.h     Mon Dec 11 19:26:39 2000
+++ linux.new/include/asm-i386/system.h Sat Dec 23 16:06:01 2000
@@ -274,7 +274,14 @@
 #ifndef CONFIG_X86_XMM
 #define mb()   __asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
 #else
-#define mb()   __asm__ __volatile__ ("sfence": : :"memory")
+#define mb()  do { \
+       if ( cpu_has_xmm ) { \
+               asm volatile("sfence": : :"memory"); \
+       } \
+       else { \
+               asm volatile("lock; addl $0,0(%%esp)": : :"memory"); \
+       } \
+} while (0)                                                            
 #endif
 #define rmb()  mb()
 #define wmb()  __asm__ __volatile__ ("": : :"memory")
diff -Nur linux/include/linux/tqueue.h linux.new/include/linux/tqueue.h
--- linux/include/linux/tqueue.h        Sat Dec 23 16:16:44 2000
+++ linux.new/include/linux/tqueue.h    Sat Dec 23 16:06:01 2000
@@ -17,6 +17,7 @@
 #include <linux/list.h>
 #include <asm/bitops.h>
 #include <asm/system.h>
+#include <asm/processor.h>
 
 /*
  * New proposed "bottom half" handlers:
diff -Nur linux/include/asm-i386/system.h linux.new/include/asm-i386/system.h
--- linux/include/asm-i386/system.h     Mon Dec 11 19:26:39 2000
+++ linux.new/include/asm-i386/system.h Sat Dec 23 16:06:01 2000
@@ -274,7 +274,14 @@
 #ifndef CONFIG_X86_XMM
 #define mb()   __asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
 #else
-#define mb()   __asm__ __volatile__ ("sfence": : :"memory")
+#define mb()  do { \
+       if ( cpu_has_xmm ) { \
+               asm volatile("sfence": : :"memory"); \
+       } \
+       else { \
+               asm volatile("lock; addl $0,0(%%esp)": : :"memory"); \
+       } \
+} while (0)                                                            
 #endif
 #define rmb()  mb()
 #define wmb()  __asm__ __volatile__ ("": : :"memory")
diff -Nur linux/include/linux/tqueue.h linux.new/include/linux/tqueue.h
--- linux/include/linux/tqueue.h        Sat Dec 23 16:16:44 2000
+++ linux.new/include/linux/tqueue.h    Sat Dec 23 16:06:01 2000
@@ -17,6 +17,7 @@
 #include <linux/list.h>
 #include <asm/bitops.h>
 #include <asm/system.h>
+#include <asm/processor.h>
 
 /*
  * New proposed "bottom half" handlers:


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