Messages in this thread Patch in this message | | | Date | Thu, 06 Apr 2006 17:57:10 +0100 | From | Brian Uhrain <> | Subject | [PATCH] Small fixes for Alpha architecture |
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Hi,
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. I've added an arch_initcall called alpha_init that is modelled after the ppc_init arch_initcall.
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. My patch just replaces the #define with an actual cpumask_t declaration for cpu_possible_map since it is used separately from cpu_present_mask in the Alpha SMP code.
Regards, Brian Uhrain diff -rudp linux-2.6.16/arch/alpha/kernel/setup.c linux-2.6.16.new/arch/alpha/kernel/setup.c --- linux-2.6.16/arch/alpha/kernel/setup.c 2006-03-20 05:53:29.000000000 +0000 +++ linux-2.6.16.new/arch/alpha/kernel/setup.c 2006-04-06 17:45:04.009752787 +0100 @@ -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> @@ -477,6 +478,22 @@ page_is_ram(unsigned long pfn) #undef PFN_PHYS #undef PFN_MAX +static struct cpu cpu_devices[NR_CPUS]; + +int __init alpha_init(void) +{ + int i; + + /* register CPU devices */ + for (i = 0; i < NR_CPUS; i++) + if (cpu_possible(i)) + register_cpu(&cpu_devices[i], i, NULL); + + return 0; +} + +arch_initcall(alpha_init); + void __init setup_arch(char **cmdline_p) { diff -rudp linux-2.6.16/arch/alpha/kernel/smp.c linux-2.6.16.new/arch/alpha/kernel/smp.c --- linux-2.6.16/arch/alpha/kernel/smp.c 2006-03-20 05:53:29.000000000 +0000 +++ linux-2.6.16.new/arch/alpha/kernel/smp.c 2006-04-06 17:45:08.810533978 +0100 @@ -69,6 +69,7 @@ static int smp_secondary_alive __initdat /* Which cpus ids came online. */ cpumask_t cpu_present_mask; +cpumask_t cpu_possible_map; cpumask_t cpu_online_map; EXPORT_SYMBOL(cpu_online_map); diff -rudp linux-2.6.16/include/asm-alpha/smp.h linux-2.6.16.new/include/asm-alpha/smp.h --- linux-2.6.16/include/asm-alpha/smp.h 2006-03-20 05:53:29.000000000 +0000 +++ linux-2.6.16.new/include/asm-alpha/smp.h 2006-04-06 17:45:08.812487103 +0100 @@ -46,9 +46,9 @@ extern struct cpuinfo_alpha cpu_data[NR_ #define raw_smp_processor_id() (current_thread_info()->cpu) extern cpumask_t cpu_present_mask; +extern cpumask_t cpu_possible_map; extern cpumask_t cpu_online_map; extern int smp_num_cpus; -#define cpu_possible_map cpu_present_mask int smp_call_function_on_cpu(void (*func) (void *info), void *info,int retry, int wait, cpumask_t cpu); | |