From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 9 Aug 2011 22:42:36 +0100 Subject: [RFC PATCH 2/8] ARM: smp: populate logical CPU mapping during boot In-Reply-To: <1312926162-22469-1-git-send-email-will.deacon@arm.com> References: <1312926162-22469-1-git-send-email-will.deacon@arm.com> Message-ID: <1312926162-22469-3-git-send-email-will.deacon@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org To allow booting Linux on a CPU with physical ID != 0, we need to provide a mapping from the logical CPU number to the physical CPU number. This patch adds such a mapping and populates it during boot. Signed-off-by: Will Deacon --- arch/arm/include/asm/smp.h | 6 ++++++ arch/arm/kernel/smp.c | 15 +++++++++++++++ 2 files changed, 21 insertions(+), 0 deletions(-) diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h index e42d96a..674ebcd 100644 --- a/arch/arm/include/asm/smp.h +++ b/arch/arm/include/asm/smp.h @@ -66,6 +66,12 @@ extern void platform_secondary_init(unsigned int cpu); extern void platform_smp_prepare_cpus(unsigned int); /* + * Logical CPU mapping. + */ +extern int __cpu_logical_map[NR_CPUS]; +#define cpu_logical_map(cpu) __cpu_logical_map[cpu] + +/* * Initial data for bringing up a secondary CPU. */ struct secondary_data { diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index d88ff02..0016665 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -39,6 +39,7 @@ #include #include #include +#include /* * as from 2.5, kernels no longer have an init_tasks structure @@ -259,6 +260,20 @@ void __ref cpu_die(void) } #endif /* CONFIG_HOTPLUG_CPU */ +int __cpu_logical_map[NR_CPUS]; + +void __init smp_setup_processor_id(void) +{ + int i; + u32 cpu = is_smp() ? read_cpuid_mpidr() & 0xff : 0; + + cpu_logical_map(0) = cpu; + for (i = 1; i < NR_CPUS; ++i) + cpu_logical_map(i) = i == cpu ? 0 : i; + + printk(KERN_INFO "Booting Linux on physical CPU %d\n", cpu); +} + /* * Called by both boot and secondaries to move global data into * per-processor storage. -- 1.7.0.4