lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

[PATCH] alpha: SMP boot fixes

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

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)
{