James Bottomley <[email protected]> wrote:
>
> > > However, introducing setup_smp_processor_id() will also work ... I'll
> > > see if I can do it in an easy way.
> >
> > It's a bit odd - I think non-zero BSPs happen a bit more often than
> > only-on-voyager.
>
> OK, here's the patch that adds this API then.
>
> James
>
> Index: voyager-init-2.6/include/linux/smp.h
> ===================================================================
> --- voyager-init-2.6.orig/include/linux/smp.h 2006-06-27 09:20:42.000000000 -0500
> +++ voyager-init-2.6/include/linux/smp.h 2006-06-27 09:23:23.000000000 -0500
> @@ -74,6 +74,15 @@
> */
> void smp_prepare_boot_cpu(void);
>
> +/*
> + * Some architectures use current_thread_info()->cpu to get the
> + * CPU, so for the boot CPU this has to be set up really early. Thus
> + * this hook is used to initialise the value if necessary
> + */
> +#ifndef ARCH_HAS_SMP_SETUP_PROCESSOR_ID
> +void smp_setup_processor_id(void) { }
> +#endif
That wants to be `static inline'.
But still. __attribute__((weak)) is wonderful for this sort of thing.
Methinks it's much neater to do:
diff -puN init/main.c~add-smp_setup_processor_id init/main.c
--- a/init/main.c~add-smp_setup_processor_id
+++ a/init/main.c
@@ -454,10 +454,17 @@ static void __init boot_cpu_init(void)
cpu_set(cpu, cpu_possible_map);
}
+static void __init __attribute__((weak)) smp_setup_processor_id(void)
+{
+}
+
asmlinkage void __init start_kernel(void)
{
char * command_line;
extern struct kernel_param __start___param[], __stop___param[];
+
+ smp_setup_processor_id();
+
/*
* Interrupts are still disabled. Do necessary setups, then
* enable them
diff -puN arch/i386/mach-voyager/voyager_smp.c~add-smp_setup_processor_id arch/i386/mach-voyager/voyager_smp.c
--- a/arch/i386/mach-voyager/voyager_smp.c~add-smp_setup_processor_id
+++ a/arch/i386/mach-voyager/voyager_smp.c
@@ -1938,3 +1938,9 @@ smp_cpus_done(unsigned int max_cpus)
{
zap_low_mappings();
}
+
+void __init
+smp_setup_processor_id(void)
+{
+ current_thread_info()->cpu = hard_smp_processor_id();
+}
diff -puN include/linux/smp.h~add-smp_setup_processor_id include/linux/smp.h
--- a/include/linux/smp.h~add-smp_setup_processor_id
+++ a/include/linux/smp.h
@@ -125,4 +125,6 @@ static inline void smp_send_reschedule(i
#define put_cpu() preempt_enable()
#define put_cpu_no_resched() preempt_enable_no_resched()
+void smp_setup_processor_id(void);
+
#endif /* __LINUX_SMP_H */
_
Note that I moved the call to smp_setup_processor_id() to be super-early.
Before the lock_kernel(), before everything. It seems better that way.
And there's lockdep init stuff in -mm which is called immediately on entry
to start_kernel() which might want to use smp_processor_id().
Is that all OK?
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