From: Wei Jiangang Date: Fri, 19 Aug 2016 03:22:36 +0000 (+0800) Subject: x86/smpboot: Check APIC ID before setting up default routing X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=384d9fe3741657c8ed8cd9bf30bc1d4611864d56;p=linux-beck.git x86/smpboot: Check APIC ID before setting up default routing This is not a bugfix, but code optimization. If the BSP's APIC ID in local APIC is unexpected, a kernel panic will occur and the system will halt. That means no need to enable APIC mode, and no reason to set up the default routing for APIC. The combination of default_setup_apic_routing() and apic_bsp_setup() are used to enable APIC mode. They two should be kept together, rather than being separated by the codes of checking APIC ID. Just like their usage in APIC_init_uniprocessor(). Signed-off-by: Wei Jiangang Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: bp@suse.de Link: http://lkml.kernel.org/r/1471576957-12961-1-git-send-email-weijg.fnst@cn.fujitsu.com Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 2a6e84a30a54..8216b997c1c9 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1316,14 +1316,13 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) break; } - default_setup_apic_routing(); - if (read_apic_id() != boot_cpu_physical_apicid) { panic("Boot APIC ID in local APIC unexpected (%d vs %d)", read_apic_id(), boot_cpu_physical_apicid); /* Or can we switch back to PIC here? */ } + default_setup_apic_routing(); cpu0_logical_apicid = apic_bsp_setup(false); pr_info("CPU%d: ", 0);