RT: remove finish_arch_switch

PATCH Applied Frank Rowand 3 participants 3 messages Jan 15, 2008 – Jan 16, 2008

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Frank Rowand

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2008-01-15 22:22 UTC #0 lore raw

PATCH 3/4 RT: remove finish_arch_switch

From: Frank Rowand <[email protected]>

This is probably just a temporary workaround for one procssor - the MIPS community will most likely want to architect a solution to this issue.

Make of preempt kernel barfs in kernel/sched.c ifdef finish_arch_switch. Remove the finish_arch_switch() for boards with TX49xx MIPS processor.

Signed-off-by Frank Rowand <[email protected]>

---

 include/asm-mips/mach-tx49xx/cpu-feature-overrides.h |    7 	7 +	0 -	0 !
 include/asm-mips/system.h                            |    3 	3 +	0 -	0 !
 2 files changed, 10 insertions(+)

include/asm-mips/mach-tx49xx/cpu-feature-overrides.h +7 -0

Index: linux-2.6.24-rc7/include/asm-mips/mach-tx49xx/cpu-feature-overrides.h
===================================================================
@@ -1,6 +1,13 @@
 #ifndef __ASM_MACH_TX49XX_CPU_FEATURE_OVERRIDES_H
 #define __ASM_MACH_TX49XX_CPU_FEATURE_OVERRIDES_H
 
+/* finish_arch_switch_empty is defined if we know finish_arch_switch() will
+ * be empty, based on the lack of features defined in this file.  This is
+ * needed because config preempt will barf in kernel/sched.c ifdef
+ * finish_arch_switch
+ */
+#define finish_arch_switch_empty
+
 #define cpu_has_llsc	1
 #define cpu_has_64bits	1
 #define cpu_has_inclusive_pcaches	0

include/asm-mips/system.h +3 -0

Index: linux-2.6.24-rc7/include/asm-mips/system.h
===================================================================
@@ -70,6 +70,8 @@ do {									\
 	(last) = resume(prev, next, task_thread_info(next));		\
 } while (0)
 
+/* preempt kernel barfs in kernel/sched.c ifdef finish_arch_switch */
+#ifndef finish_arch_switch_empty
 #define finish_arch_switch(prev)					\
 do {									\
 	if (cpu_has_dsp)						\

@@ -77,6 +79,7 @@ do {									\
 	if (cpu_has_userlocal)						\
 		write_c0_userlocal(current_thread_info()->tp_value);	\
 } while (0)
+#endif
 
 static inline unsigned long __xchg_u32(volatile int * m, unsigned int val)
 {

Steven Rostedt

2008-01-16 02:15 UTC #1 lore raw

Quoted 26 lines · Frank Rowand

From: Frank Rowand <[email protected]>
Index: linux-2.6.24-rc7/include/asm-mips/mach-tx49xx/cpu-feature-overrides.h
===================================================================
include/asm-mips/mach-tx49xx/cpu-feature-overrides.h +7 -0
@@ -1,6 +1,13 @@
 #ifndef __ASM_MACH_TX49XX_CPU_FEATURE_OVERRIDES_H
 #define __ASM_MACH_TX49XX_CPU_FEATURE_OVERRIDES_H
 
+/* finish_arch_switch_empty is defined if we know finish_arch_switch() will
+ * be empty, based on the lack of features defined in this file.  This is
+ * needed because config preempt will barf in kernel/sched.c ifdef
+ * finish_arch_switch
+ */
+#define finish_arch_switch_empty
+
 #define cpu_has_llsc	1
 #define cpu_has_64bits	1
 #define cpu_has_inclusive_pcaches	0
Index: linux-2.6.24-rc7/include/asm-mips/system.h
===================================================================

include/asm-mips/system.h do { \ · line 74

Quoted 5 lines

include/asm-mips/system.h +2 -0

@@ -70,6 +70,8 @@ do {									\
 	(last) = resume(prev, next, task_thread_info(next));		\
 } while (0)
 
+/* preempt kernel barfs in kernel/sched.c ifdef finish_arch_switch */
+#ifndef finish_arch_switch_empty

I'll take this patch for now, but currently it looks like a hack. I know you said that, but I'm hoping someone will come up with a better solution.

Thanks,

-- Steve

Quoted 19 lines

include/asm-mips/system.h +1 -1
 #define finish_arch_switch(prev)					\
 do {									\
 	if (cpu_has_dsp)						\
@@ -77,6 +79,7 @@ do {									\
 	if (cpu_has_userlocal)						\
 		write_c0_userlocal(current_thread_info()->tp_value);	\
 } while (0)
+#endif
 
 static inline unsigned long __xchg_u32(volatile int * m, unsigned int val)
 {
 
 
 
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Rowand, Frank

2008-01-16 02:19 UTC #2 lore raw

Steve,

Thanks, I'll bring this up over on the linux-mips list to see how they really want to handle it.

-Frank

-----Original Message-----
From: Steven Rostedt [mailto:[email protected]]
Sent: Tue 1/15/2008 6:14 PM
To: Rowand, Frank
Cc: [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH 3/4] RT: remove finish_arch_switch