linux-kernel - Re: [PATCH v9] x86, apic, kexec, Documentation: Add disable_cpu

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Message-ID: <529ECAAB.8040309@jp.fujitsu.com>
Date:	Wed, 04 Dec 2013 15:24:43 +0900
From:	HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
To:	Vivek Goyal <vgoyal@...hat.com>
CC:	"H. Peter Anvin" <hpa@...ux.intel.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Borislav Petkov <bp@...en8.de>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jingbai Ma <jingbai.ma@...com>,
	Jerry Hoemann <jerry.hoemann@...com>
Subject: Re: [PATCH v9] x86, apic, kexec, Documentation: Add disable_cpu_apic
 kernel parameter

(2013/12/04 12:08), HATAYAMA Daisuke wrote:
> (2013/12/04 0:25), Vivek Goyal wrote:
>> On Tue, Dec 03, 2013 at 10:32:26AM +0900, HATAYAMA Daisuke wrote:
>>
>> [..]
>>>
>>> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
>>> index 50680a5..dd77bec 100644
>>> --- a/Documentation/kernel-parameters.txt
>>> +++ b/Documentation/kernel-parameters.txt
>>> @@ -774,6 +774,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>>>       disable=    [IPV6]
>>>               See Documentation/networking/ipv6.txt.
>>>
>>> +    disable_cpu_apicid= [X86,APIC,KEXEC,SMP]
>>
>> Hi Hatayama,
>>
>> We are almost there. A minor nit. Why have we specified KEXEC here. This
>> parameter disabled_cpu_apicid does not seem to dependon CONFIG_KEXEC?
>>
>> Jerry, this patch looks good to me. Does it work on your system?
>>
>
> Because primary user for the option is currently kexec/kdump only.
>
> I referred to acpi_rsdp description:
>
>          acpi_rsdp=      [ACPI,EFI,KEXEC]
>                          Pass the RSDP address to the kernel, mostly used
>                          on machines running EFI runtime service to boot the
>                          second kernel for kdump.
>

Indo-san, who introduced acpi_rsdp and KEXEC tag, told me that historical reason
why KEXEC tag was introduced. disable_cpu_apicid is generic at least in the
current version, so the tag doesn't need to be specified here.

I'll post a new version soon.

-- 
Thanks.
HATAYAMA, Daisuke

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