On 10/29/13 at 10:21pm, Baoquan He wrote: > Hi, > > I am reviewing this patchset, and found there's a cpu0 hotplug feature Forget to attach the link of patch for cpu0 hotplug. http://lwn.net/Articles/475018/ In this patchset, BSP is also called CPU0. > posted by intel which we can borrow an idea from. In that implementation, > CPU0 is waken up by nmi not INIT to avoid the realmode bootstrap code > execution. I tried it by below patch which includes one line of change. > > By console printing, I got the boot cpu is always 0(namely cpu=0), > however the apicid related to each processor keeps the same as in 1st > kernel. In my HP Z420 machine, the apicid for BSP is 0, so I just make a > test patch which depends on the fact that apicid for BSP is 0. Maybe > generally the apicid for BSP can't be guaranteed, then passing it from > 1st kernel to 2nd kernel in cmdline is very helpful, just as you have > done for disable_cpu_apic. > > On my HP z420, I add nr_cpus=4 in /etc/sysconfig/kdump, and then execute > below command, then 3 APs (1 boot cpu and 2 AP) can be waken up > correctly, but BSP failed because NMI received for unknown reason 21 on > CPU0. I think I need further check why BSP failed to wake up by nmi. But > 3 processors are brought up successfully and kdump is successful too. > > sudo taskset -c 1 sh -c "echo c >/proc/sysrq-trigger" > > [ 0.296831] smpboot: Booting Node 0, Processors # 1 > [ 0.302095] > *****************************************************cpu=1, apicid=0, wakeup_cpu_via_init_nmi > [ 0.311942] cpu=1, apicid=0, register_nmi_handlercpu=1, apicid=0, wakeup_secondary_cpu_via_nmi > [ 0.320826] Uhhuh. NMI received for unknown reason 21 on CPU 0. > [ 0.327129] Do you have a strange power saving mode enabled? > [ 0.333858] Dazed and confused, but trying to continue > [ 0.339290] cpu=1, apicid=0, wakeup_cpu_via_init_nmi > [ 2.409099] Uhhuh. NMI received for unknown reason 21 on CPU 0. > [ 2.415393] Do you have a strange power saving mode enabled? > [ 2.421142] Dazed and confused, but trying to continue > [ 5.379519] smpboot: CPU1: Not responding > [ 5.383692] NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter. > > diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > index 6cacab6..e45fe5b 100644 > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -702,7 +702,7 @@ wakeup_cpu_via_init_nmi(int cpu, unsigned long > start_ip, int apicid, > /* > * Wake up AP by INIT, INIT, STARTUP sequence. > */ > - if (cpu) > + if (cpu && apicid) > return wakeup_secondary_cpu_via_init(apicid, start_ip); > > /* > > > > On 10/23/13 at 12:01am, HATAYAMA Daisuke wrote: > > This patch set is to allow kdump 2nd kernel to wake up multiple CPUs > > even if 1st kernel crashs on some AP, a continueing work from: > > > > [PATCH v3 0/2] x86, apic, kdump: Disable BSP if boot cpu is AP > > https://lkml.org/lkml/2013/10/16/300. > > > > In this version, basic design has changed. Now users need to figure > > out initial APIC ID of BSP in the 1st kernel and configures kernel > > parameter for the 2nd kernel manually using disable_cpu_apic kernel > > parameter to be newly introduced in this patch set. This design is > > more flexible than the previous version in that we no longer have to > > rely on ACPI/MP table to get initial APIC ID of BSP. > > > > Sorry, this patch set have not include in-source documentation > > requested by Borislav Petkov yet, but I'll post it later separately, > > which would be better to focus on documentation reviewing. > > > > ChangeLog > > > > v3 => v4) > > > > - Rebased on top of v3.12-rc6 > > > > - Basic design has been changed. Now users need to figure out initial > > APIC ID of BSP in the 1st kernel and configures kernel parameter for > > the 2nd kernel manually using disable_cpu_apic kernel parameter to > > be newly introduced in this patch set. This design is more flexible > > than the previous version in that we no longer have to rely on > > ACPI/MP table to get initial APIC ID of BSP. > > > > v2 => v3) > > > > - Change default value of boot_cpu_is_bsp to true. > > > > - Before executing rdmsr(MSR_IA32_APICBASE), check if the number of > > processor family is larger than or equal to 6 in order to avoid > > invalid opcode exception on processors where MSR_IA32_APICBASE is > > not supported. > > > > v1 => v2) > > > > - Rebased on top of v3.12-rc5. > > > > - Fix linking time error of boot_cpu_is_bsp_init() in case of > > CONFIG_LOCAL_APIC disabled by adding empty static inline function > > instead. > > > > - Fix missing feature check by means of cpu_has_apic macro in > > boot_cpu_is_bsp_init() before calling rdmsr_safe(MSR_IA32_APICBASE). > > > > NOTE: I've checked local apic-present case only; I don't have any > > x86 processor without local apic. > > > > - Add __init annotation to boot_cpu_is_bsp_init(). > > > > Test > > > > - built with and without CONFIG_LOCAL_APIC > > - tested x86_64 in case of acpi and MP table > > > > --- > > > > HATAYAMA Daisuke (3): > > x86, apic: Don't count the CPU with BP flag from MP table as booting-up CPU > > x86, apic: Add disable_cpu_apicid kernel parameter > > Documentation, x86, apic, kexec: Add disable_cpu_apicid kernel parameter > > > > > > Documentation/kernel-parameters.txt | 9 +++++++++ > > arch/x86/kernel/apic/apic.c | 29 +++++++++++++++++++++++++++++ > > arch/x86/kernel/mpparse.c | 1 - > > 3 files changed, 38 insertions(+), 1 deletion(-) > > > > -- > > > > Thanks. > > HATAYAMA, Daisuke > > > > _______________________________________________ > > kexec mailing list > > kexec at lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/kexec > > _______________________________________________ > kexec mailing list > kexec at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec
