From 917b1f78a9871a1985004df09ed1eb2e0dc3bf4f Mon Sep 17 00:00:00 2001 From: Brian Uhrain says Date: Mon, 10 Apr 2006 22:53:16 -0700 Subject: [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 - 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 Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/alpha/kernel/setup.c | 17 +++++++++++++++++ arch/alpha/kernel/smp.c | 8 +++----- 2 files changed, 20 insertions(+), 5 deletions(-) (limited to 'arch/alpha/kernel') diff --git a/arch/alpha/kernel/setup.c b/arch/alpha/kernel/setup.c index a15e18a0025..558b8336855 100644 --- a/arch/alpha/kernel/setup.c +++ b/arch/alpha/kernel/setup.c @@ -24,6 +24,7 @@ #include /* CONFIG_ALPHA_LCA etc */ #include #include +#include #include #include #include @@ -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) { diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c index 02c2db08114..185255416e8 100644 --- a/arch/alpha/kernel/smp.c +++ b/arch/alpha/kernel/smp.c @@ -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); } -- cgit v1.2.3