linux-kernel - Re: [PATCH] kdump, x86: report actual value of phys

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Message-ID: <54646C1D.1050102@jp.fujitsu.com>
Date:	Thu, 13 Nov 2014 17:30:21 +0900
From:	"HATAYAMA, Daisuke" <d.hatayama@...fujitsu.com>
To:	Petr Tesarik <ptesarik@...e.cz>
CC:	vgoyal@...hat.com, kumagai-atsushi@....nes.nec.co.jp,
	anderson@...hat.com, kexec@...ts.infradead.org,
	ebiederm@...ssion.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kdump, x86: report actual value of phys_base in VMCOREINFO



(2014/11/13 17:06), Petr Tesarik wrote:
> On Thu, 13 Nov 2014 09:17:09 +0900 (JST)
> HATAYAMA Daisuke <d.hatayama@...fujitsu.com> wrote:
>
>> From: Vivek Goyal <vgoyal@...hat.com>
>> Subject: Re: [PATCH] kdump, x86: report actual value of phys_base in VMCOREINFO
>> Date: Wed, 12 Nov 2014 17:12:05 -0500
>>
>>> On Wed, Nov 12, 2014 at 03:40:42PM +0900, HATAYAMA Daisuke wrote:
>>>> Currently, VMCOREINFO note information reports the virtual address of
>>>> phys_base that is assigned to symbol phys_base. But this doesn't make
>>>> sense because to refer to value of the phys_base, it's necessary to
>>>> get the value of phys_base itself we are now about to refer to.
>>>>
>>>
>>> Hi Hatayama,
>>>
>>> /proc/vmcore ELF headers have virtual address information and using
>>> that you should be able to read actual value of phys_base. gdb deals
>>> with virtual addresses all the time and can read value of any symbol
>>> using those headers.
>>>
>>> So I am not sure what's the need for exporting actual value of
>>> phys_base.
>>>
>>
>> Sorry, my logic in the patch description was wrong. For /proc/vmcore,
>> there's enough information for makedumpdile to get phys_base. It's
>> correct. The problem here is that other crash dump mechanisms that run
>> outside Linux kernel independently don't have information to get
>> phys_base.
>
> Yes, but these mechanisms won't be able to read VMCOREINFO either, will
> they?
>

I don't intend such sophisticated function only by VMCOREINFO.
Search vmcore for VMCOREINFO using strings + grep before opening it by crash.
I intend that only here.

-- 
Thanks.
HATAYAMA, Daisuke

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