[PATCH] kdump, x86: report actual value of phys_base in VMCOREINFO

HATAYAMA, Daisuke d.hatayama at jp.fujitsu.com
Thu Nov 13 00:30:21 PST 2014

(2014/11/13 17:06), Petr Tesarik wrote:
> On Thu, 13 Nov 2014 09:17:09 +0900 (JST)
> HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com> wrote:
>> From: Vivek Goyal <vgoyal at redhat.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.


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