[PATCH] alpha: SMP boot fixes
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>
diff --git a/arch/alpha/kernel/setup.c b/arch/alpha/kernel/setup.c
index a15e18a..558b833 100644
--- a/arch/alpha/kernel/setup.c
+++ b/arch/alpha/kernel/setup.c
@@ -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 @@
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)
{
