From 681ee44d40d7c93b42118320e4620d07d8704fd6 Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Tue, 9 Feb 2010 18:01:44 -0800 Subject: x86, apic: Don't use logical-flat mode when CPU hotplug may exceed 8 CPUs We need to fall back from logical-flat APIC mode to physical-flat mode when we have more than 8 CPUs. However, in the presence of CPU hotplug(with bios listing not enabled but possible cpus as disabled cpus in MADT), we have to consider the number of possible CPUs rather than the number of current CPUs; otherwise we may cross the 8-CPU boundary when CPUs are added later. 32bit apic code can use more cleanups (like the removal of vendor checks in 32bit default_setup_apic_routing()) and more unifications with 64bit code. Yinghai has some patches in works already. This patch addresses the boot issue that is reported in the virtualization guest context. [ hpa: incorporated function annotation feedback from Yinghai Lu ] Signed-off-by: Suresh Siddha LKML-Reference: <1265767304.2833.19.camel@sbs-t61.sc.intel.com> Acked-by: Shaohui Zheng Reviewed-by: Yinghai Lu Cc: Signed-off-by: H. Peter Anvin --- arch/x86/kernel/smpboot.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch/x86/kernel/smpboot.c') diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 678d0b8c26f3..b4e870cbdc60 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1083,9 +1083,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) set_cpu_sibling_map(0); enable_IR_x2apic(); -#ifdef CONFIG_X86_64 default_setup_apic_routing(); -#endif if (smp_sanity_check(max_cpus) < 0) { printk(KERN_INFO "SMP disabled\n"); -- cgit v1.2.3 From 2b633e3fac5efada088b57d31e65401f22bcc18f Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Wed, 10 Feb 2010 01:20:37 -0800 Subject: smp: Use nr_cpus= to set nr_cpu_ids early On x86, before prefill_possible_map(), nr_cpu_ids will be NR_CPUS aka CONFIG_NR_CPUS. Add nr_cpus= to set nr_cpu_ids. so we can simulate cpus <=8 are installed on normal config. -v2: accordging to Christoph, acpi_numa_init should use nr_cpu_ids in stead of NR_CPUS. -v3: add doc in kernel-parameters.txt according to Andrew. Signed-off-by: Yinghai Lu LKML-Reference: <1265793639-15071-34-git-send-email-yinghai@kernel.org> Acked-by: Linus Torvalds Signed-off-by: H. Peter Anvin Cc: Tony Luck --- arch/x86/kernel/smpboot.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'arch/x86/kernel/smpboot.c') diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 678d0b8c26f3..eff2fe175422 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1213,11 +1213,12 @@ __init void prefill_possible_map(void) total_cpus = max_t(int, possible, num_processors + disabled_cpus); - if (possible > CONFIG_NR_CPUS) { + /* nr_cpu_ids could be reduced via nr_cpus= */ + if (possible > nr_cpu_ids) { printk(KERN_WARNING "%d Processors exceeds NR_CPUS limit of %d\n", - possible, CONFIG_NR_CPUS); - possible = CONFIG_NR_CPUS; + possible, nr_cpu_ids); + possible = nr_cpu_ids; } printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n", -- cgit v1.2.3