From: Borislav Petkov <bp@alien8.de> To: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> Cc: ebiederm@xmission.com, vgoyal@redhat.com, akpm@linux-foundation.org, hpa@linux.intel.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, jingbai.ma@hp.com Subject: Re: [PATCH 2/2] x86, apic: Disable BSP if boot cpu is AP Date: Sat, 31 Aug 2013 07:22:53 +0200 [thread overview] Message-ID: <20130831052252.GC12617@x1.alien8.de> (raw) In-Reply-To: <20130829092804.5476.95588.stgit@localhost6.localdomain6> On Thu, Aug 29, 2013 at 06:28:04PM +0900, HATAYAMA Daisuke wrote: > diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c > index 66cab35..fd969d1 100644 > --- a/arch/x86/kernel/apic/apic.c > +++ b/arch/x86/kernel/apic/apic.c > @@ -2113,13 +2113,29 @@ void disconnect_bsp_APIC(int virt_wire_setup) > apic_write(APIC_LVT1, value); > } > > -void generic_processor_info(int apicid, int version) > +void generic_processor_info(int apicid, bool isbsp, int version) > { > int cpu, max = nr_cpu_ids; > bool boot_cpu_detected = physid_isset(boot_cpu_physical_apicid, > phys_cpu_present_map); > > /* > + * If boot cpu is AP, we now don't have any way to initialize > + * BSP. To save memory consumed, we disable BSP this case and I don't think we disable the BSP just so that we save memory and rather because we hang in the kdump kernel otherwise, right? > + * use (N-1)-cpus. > + */ > + if (isbsp && !boot_cpu_is_bsp) { This variable naming looks confusing, IMHO. It would probably be more understandable if 'isbsp' was called 'boot_cpu' to denote that this is the CPU we're booting on currently. The comment above it then explains that it is an AP and it might also refer to the issue why we're doing that. > + int thiscpu = num_processors + disabled_cpus; > + > + pr_warning("ACPI: The boot cpu is not BSP. " > + "The BSP Processor %d/0x%x ignored.\n", > + thiscpu, apicid); Visible comment, so needs a bit of correcting: "ACPI: We're not booting on the BSP; BSP %d/0x%x ignored." > + > + disabled_cpus++; > + return; > + } > + > + /* > * If boot cpu has not been detected yet, then only allow upto > * nr_cpu_ids - 1 processors and keep one slot free for boot cpu > */ Thanks. -- Regards/Gruss, Boris.
WARNING: multiple messages have this Message-ID (diff)
From: Borislav Petkov <bp@alien8.de> To: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> Cc: jingbai.ma@hp.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, ebiederm@xmission.com, akpm@linux-foundation.org, hpa@linux.intel.com, vgoyal@redhat.com Subject: Re: [PATCH 2/2] x86, apic: Disable BSP if boot cpu is AP Date: Sat, 31 Aug 2013 07:22:53 +0200 [thread overview] Message-ID: <20130831052252.GC12617@x1.alien8.de> (raw) In-Reply-To: <20130829092804.5476.95588.stgit@localhost6.localdomain6> On Thu, Aug 29, 2013 at 06:28:04PM +0900, HATAYAMA Daisuke wrote: > diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c > index 66cab35..fd969d1 100644 > --- a/arch/x86/kernel/apic/apic.c > +++ b/arch/x86/kernel/apic/apic.c > @@ -2113,13 +2113,29 @@ void disconnect_bsp_APIC(int virt_wire_setup) > apic_write(APIC_LVT1, value); > } > > -void generic_processor_info(int apicid, int version) > +void generic_processor_info(int apicid, bool isbsp, int version) > { > int cpu, max = nr_cpu_ids; > bool boot_cpu_detected = physid_isset(boot_cpu_physical_apicid, > phys_cpu_present_map); > > /* > + * If boot cpu is AP, we now don't have any way to initialize > + * BSP. To save memory consumed, we disable BSP this case and I don't think we disable the BSP just so that we save memory and rather because we hang in the kdump kernel otherwise, right? > + * use (N-1)-cpus. > + */ > + if (isbsp && !boot_cpu_is_bsp) { This variable naming looks confusing, IMHO. It would probably be more understandable if 'isbsp' was called 'boot_cpu' to denote that this is the CPU we're booting on currently. The comment above it then explains that it is an AP and it might also refer to the issue why we're doing that. > + int thiscpu = num_processors + disabled_cpus; > + > + pr_warning("ACPI: The boot cpu is not BSP. " > + "The BSP Processor %d/0x%x ignored.\n", > + thiscpu, apicid); Visible comment, so needs a bit of correcting: "ACPI: We're not booting on the BSP; BSP %d/0x%x ignored." > + > + disabled_cpus++; > + return; > + } > + > + /* > * If boot cpu has not been detected yet, then only allow upto > * nr_cpu_ids - 1 processors and keep one slot free for boot cpu > */ Thanks. -- Regards/Gruss, Boris. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2013-08-31 5:22 UTC|newest] Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-08-29 9:27 [PATCH 0/2] x86, apic: Disable BSP if boot cpu is AP HATAYAMA Daisuke 2013-08-29 9:27 ` HATAYAMA Daisuke 2013-08-29 9:27 ` [PATCH 1/2] x86, apic: Add boot_cpu_is_bsp() to check if boot cpu is BSP HATAYAMA Daisuke 2013-08-29 9:27 ` HATAYAMA Daisuke 2013-10-09 23:15 ` [tip:x86/bsp-hotplug] " tip-bot for HATAYAMA Daisuke 2013-08-29 9:28 ` [PATCH 2/2] x86, apic: Disable BSP if boot cpu is AP HATAYAMA Daisuke 2013-08-29 9:28 ` HATAYAMA Daisuke 2013-08-31 5:22 ` Borislav Petkov [this message] 2013-08-31 5:22 ` Borislav Petkov 2013-09-02 2:32 ` HATAYAMA Daisuke 2013-09-02 2:32 ` HATAYAMA Daisuke 2013-09-02 7:13 ` Borislav Petkov 2013-09-02 7:13 ` Borislav Petkov 2013-09-02 9:42 ` HATAYAMA Daisuke 2013-09-02 9:42 ` HATAYAMA Daisuke 2013-09-04 6:12 ` Borislav Petkov 2013-09-04 6:12 ` Borislav Petkov 2013-09-09 6:18 ` HATAYAMA Daisuke 2013-09-09 6:18 ` HATAYAMA Daisuke 2013-10-09 23:16 ` [tip:x86/bsp-hotplug] " tip-bot for HATAYAMA Daisuke 2013-10-12 17:31 ` H. Peter Anvin 2013-10-12 17:42 ` Ingo Molnar 2013-11-11 19:54 ` H. Peter Anvin 2013-11-12 10:20 ` HATAYAMA Daisuke 2013-11-12 15:35 ` H. Peter Anvin 2013-08-29 13:54 ` [PATCH 0/2] " H. Peter Anvin 2013-08-29 13:54 ` H. Peter Anvin 2013-08-29 23:37 ` Eric W. Biederman 2013-08-29 23:37 ` Eric W. Biederman 2013-08-30 12:48 ` Vivek Goyal 2013-08-30 12:48 ` Vivek Goyal 2013-08-29 23:51 ` HATAYAMA Daisuke 2013-08-29 23:51 ` HATAYAMA Daisuke 2013-08-30 15:43 ` H. Peter Anvin 2013-08-30 15:43 ` H. Peter Anvin 2013-10-09 20:20 ` Vivek Goyal 2013-10-09 20:20 ` Vivek Goyal 2013-10-14 9:03 ` Petr Tesarik 2013-10-14 9:03 ` Petr Tesarik
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