From: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
To: Borislav Petkov <bp@alien8.de>
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: Mon, 02 Sep 2013 18:42:44 +0900 [thread overview]
Message-ID: <52245D94.5050702@jp.fujitsu.com> (raw)
In-Reply-To: <20130902071318.GA3406@x1.alien8.de>
(2013/09/02 16:13), Borislav Petkov wrote:
> On Mon, Sep 02, 2013 at 11:32:59AM +0900, HATAYAMA Daisuke wrote:
>> As you suggest, boot_cpu seems more understandable also to me. BTW,
>> please notice that it doesn't denote that the CPU we're booting on
>> currently, but that the CPU with BSP flag set.
>
> Hmm, by "BSP flag set" you mean it is the first LAPIC entry in the MADT,
> correct? At least this is the case when you set isbsp to true. Because,
> there's also the BSC flag in APIC_BAR (MSR 0x1b) which denotes the
> bootstrapping core on node 0.
>
The reason why I don't lookup BSP flag in MSR is that it's impossible.
To read MSR of some CPU, we need to use rdmsr instruction on the CPU.
However, in case of this issue, the BSP is halting or running in
the kdump 1st kernel.
A whole explanation is written in the patch description.
--
Thanks.
HATAYAMA, Daisuke
next prev parent reply other threads:[~2013-09-02 9:43 UTC|newest]
Thread overview: 23+ 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 ` [PATCH 1/2] x86, apic: Add boot_cpu_is_bsp() to check if boot cpu is BSP 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
2013-08-31 5:22 ` Borislav Petkov
2013-09-02 2:32 ` HATAYAMA Daisuke
2013-09-02 7:13 ` Borislav Petkov
2013-09-02 9:42 ` HATAYAMA Daisuke [this message]
2013-09-04 6:12 ` Borislav Petkov
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 23:37 ` Eric W. Biederman
2013-08-30 12:48 ` Vivek Goyal
2013-08-29 23:51 ` HATAYAMA Daisuke
2013-08-30 15:43 ` H. Peter Anvin
2013-10-09 20:20 ` Vivek Goyal
2013-10-14 9:03 ` Petr Tesarik
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