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[PATCH] alpha: SMP boot fixes

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I've encountered two problems with 2.6.16 and newer kernels on my API CS20
(dual 833MHz Alpha 21264b processors).  The first is the kernel OOPSing
because of a NULL pointer dereference while trying to populate SysFS with the
CPU information.  The other is that only one processor was being brought up.
I've included a small Alpha-specific patch that fixes both problems.

The first problem was caused by the CPUs never being properly registered using
register_cpu(), the way it's done on other architectures.

The second problem has to do with the removal of hwrpb_cpu_present_mask in
arch/alpha/kernel/smp.c.  In setup_smp() in the 2.6.15 kernel sources,
hwrpb_cpu_present_mask has a bit set for each processor that is probed, and
afterwards cpu_present_mask is set to the cpumask for the boot CPU.  In the
same function of the same file in the 2.6.16 sources, instead of
hwrpb_cpu_present_mask being set, cpu_possible_map is updated for each probed
CPU.  cpu_present_mask is still set to the cpumask of the boot CPU afterwards.
 The problem lies in include/asm-alpha/smp.h, where cpu_possible_map is
#define'd to be cpu_present_mask.

Cleanups from: Ivan Kokshaysky <ink@jurassic.park.msu.ru>

 - cpu_present_mask and cpu_possible_map are essentially the same thing
   on alpha, as it doesn't support CPU hotplug;
 - allocate "struct cpu" only for present CPUs, like sparc64 does.
   Static array of "struct cpu" is just a waste of memory.

Signed-off-by: Brian Uhrain <buhrain@rosettastone.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Brian Uhrain says 2006-04-10 22:53:16 -07:00 committed by Linus Torvalds
parent 1c08ca89b0
commit 917b1f78a9
2 changed files with 20 additions and 5 deletions
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17
arch/alpha/kernel/setup.c
View file

@ -24,6 +24,7 @@
#include <linux/config.h> /* CONFIG_ALPHA_LCA etc */
#include <linux/mc146818rtc.h>
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/string.h>
@ -471,6 +472,22 @@ page_is_ram(unsigned long pfn)
return 0;
}
static int __init
register_cpus(void)
{
int i;
for_each_possible_cpu(i) {
struct cpu *p = kzalloc(sizeof(*p), GFP_KERNEL);
if (!p)
return -ENOMEM;
register_cpu(p, i, NULL);
}
return 0;
}
arch_initcall(register_cpus);
void __init
setup_arch(char **cmdline_p)
{

8
arch/alpha/kernel/smp.c
View file

@ -439,7 +439,7 @@ setup_smp(void)
if ((cpu->flags & 0x1cc) == 0x1cc) {
smp_num_probed++;
/* Assume here that "whami" == index */
cpu_set(i, cpu_possible_map);
cpu_set(i, cpu_present_mask);
cpu->pal_revision = boot_cpu_palrev;
}
@ -450,9 +450,8 @@ setup_smp(void)
}
} else {
smp_num_probed = 1;
cpu_set(boot_cpuid, cpu_possible_map);
cpu_set(boot_cpuid, cpu_present_mask);
}
cpu_present_mask = cpumask_of_cpu(boot_cpuid);
printk(KERN_INFO "SMP: %d CPUs probed -- cpu_present_mask = %lx\n",
smp_num_probed, cpu_possible_map.bits[0]);
@ -488,9 +487,8 @@ void __devinit
smp_prepare_boot_cpu(void)
{
/*
* Mark the boot cpu (current cpu) as both present and online
* Mark the boot cpu (current cpu) as online
*/
cpu_set(smp_processor_id(), cpu_present_mask);
cpu_set(smp_processor_id(), cpu_online_map);
}