On Mon, 2006-06-26 at 22:03 -0700, Andrew Morton wrote:
> Well. It's the assembly code which chose to call start_kernel(). It could
> call something else.
arch_start_kernel maybe? I still think that's a bit of a non-obvious
alteration to a very well ingrained existing procedure.
> > > A less wholesome but perhaps simpler solution would be to call the new
> > > setup_smp_processor_id() on entry to start_kernel().
> >
> > I was wondering about simply replacing boot_cpu_init() with
> > smp_prepare_boot_cpu(). By and large they do the same thing on most
> > archs, and mostly they don't seem to depend on setup_arch() having been
> > called.
>
> That won't fix the other bugs - we're presently calling printk() prior to
> setup_arch(), and printk uses smp_procesor_id().
No, I mean call smp_prepare_boot_cpu() where boot_cpu_init() is now
(i.e. *before* setup_arch). On all the arch's I know (parisc, i386 and
voyager) this function does nothing but set up the cpu map as
boot_cpu_init() does. Of course, this change would break any arch that
relied on setup_arch() being called before smp_prepare_boot_cpu() ...
> > 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
+
#else /* !SMP */
/*
@@ -96,6 +105,7 @@
static inline void smp_send_reschedule(int cpu) { }
#define num_booting_cpus() 1
#define smp_prepare_boot_cpu() do {} while (0)
+#define smp_setup_processor_id() do {} while (0)
#endif /* !SMP */
Index: voyager-init-2.6/init/main.c
===================================================================
--- voyager-init-2.6.orig/init/main.c 2006-06-27 09:19:12.000000000 -0500
+++ voyager-init-2.6/init/main.c 2006-06-27 09:20:30.000000000 -0500
@@ -455,6 +455,7 @@
* enable them
*/
lock_kernel();
+ smp_setup_processor_id();
boot_cpu_init();
page_address_init();
printk(KERN_NOTICE);
Index: voyager-init-2.6/include/asm-i386/smp.h
===================================================================
--- voyager-init-2.6.orig/include/asm-i386/smp.h 2006-06-27 09:23:38.000000000 -0500
+++ voyager-init-2.6/include/asm-i386/smp.h 2006-06-27 09:24:29.000000000 -0500
@@ -8,6 +8,7 @@
#include <linux/kernel.h>
#include <linux/threads.h>
#include <linux/cpumask.h>
+#include "mach_smp.h"
#endif
#ifdef CONFIG_X86_LOCAL_APIC
Index: voyager-init-2.6/include/asm-i386/mach-default/mach_smp.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ voyager-init-2.6/include/asm-i386/mach-default/mach_smp.h 2006-06-27 09:42:16.000000000 -0500
@@ -0,0 +1,13 @@
+/*
+ * include/asm-i386/mach-default/mach_smp.h
+ *
+ * Machine specific SMP definitions
+ */
+#ifndef _MACH_SMP_H
+/*
+ * The boot CPU is always zero for apic based systems
+ */
+#define ARCH_HAS_SMP_SETUP_PROCESSOR_ID
+#define smp_setup_processor_id() \
+ do { current_thread_info()->cpu = 0; } while (0)
+#endif
Index: voyager-init-2.6/include/asm-i386/mach-voyager/mach_smp.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ voyager-init-2.6/include/asm-i386/mach-voyager/mach_smp.h 2006-06-27 09:30:30.000000000 -0500
@@ -0,0 +1,9 @@
+/*
+ * include/asm-i386/mach-voyager/mach_smp.h
+ *
+ * Machine specific SMP definitions
+ */
+#ifndef _MACH_SMP_H
+#define ARCH_HAS_SMP_SETUP_PROCESSOR_ID
+extern void smp_setup_processor_id(void);
+#endif
Index: voyager-init-2.6/arch/i386/mach-voyager/voyager_smp.c
===================================================================
--- voyager-init-2.6.orig/arch/i386/mach-voyager/voyager_smp.c 2006-06-27 09:30:46.000000000 -0500
+++ voyager-init-2.6/arch/i386/mach-voyager/voyager_smp.c 2006-06-27 09:31:44.000000000 -0500
@@ -1916,6 +1916,12 @@
cpu_set(smp_processor_id(), cpu_present_map);
}
+void __init
+smp_setup_processor_id(void)
+{
+ current_thread_info()->cpu = hard_smp_processor_id();
+}
+
int __devinit
__cpu_up(unsigned int cpu)
{
-
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