Re: [PATCH 3/4] RT: remove finish_arch_switch

From: Steven Rostedt
Date: Tue Jan 15 2008 - 21:15:28 EST


On Tue, Jan 15, 2008 at 02:20:46PM -0800, Frank Rowand wrote:
> From: Frank Rowand <frank.rowand@xxxxxxxxxxx>
>
>
> Index: linux-2.6.24-rc7/include/asm-mips/mach-tx49xx/cpu-feature-overrides.h
> ===================================================================
> --- linux-2.6.24-rc7.orig/include/asm-mips/mach-tx49xx/cpu-feature-overrides.h
> +++ 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
> Index: linux-2.6.24-rc7/include/asm-mips/system.h
> ===================================================================
> --- linux-2.6.24-rc7.orig/include/asm-mips/system.h
> +++ 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

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

> #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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