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From: Baoquan He <bhe@redhat.com>
To: "lizhijian@fujitsu.com" <lizhijian@fujitsu.com>
Cc: "kexec@lists.infradead.org" <kexec@lists.infradead.org>
Subject: Re: where/how 2nd kernel's elfcorehdr_addr comes from
Date: Sat, 5 Nov 2022 09:49:44 +0800	[thread overview]
Message-ID: <Y2XBOErUs8qQE0Ki@MiWiFi-R3L-srv> (raw)
In-Reply-To: <72d4be26-1711-aab8-50ed-8af538b4f6eb@fujitsu.com>

On 11/04/22 at 09:03am, lizhijian@fujitsu.com wrote:
> Hi folks,
> 
> I'm trying to add pmem's metadata(located at pmem device) to 
> /proc/vmcore. To accomplish this, I think
> 
> something i need to know is where the contents of /proc/vmcore come 
> from, and then append
> 
> something into it.
> 
> I have read 
> https://opensource.com/article/17/6/kdump-usage-and-internals, and knew 
> /proc/vmcore is a elf file.
> 
> It mentioned that "Creates /proc/vmcore as per elfcorehdr information 
> received", but i don't get how it
> 
> elfcorehdr(maybe elfcorehdr_addr) be assigned in 2nd kernel.
> 
> I tried to grep it in the kernel source, but still no answer.  So i deep 
> hope you guys can give me some hints or answer.

Since you have studied this, so:
crash_prepare_elf64_headers() is the place where elf header of vmcore is
contructed in 1st kernel. And in crash_load_segments() it's prepared to
be passed out. I am talking about x86, and kexec_file load. You should
be able to find the similar thing in user space code.


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      parent reply	other threads:[~2022-11-05  1:50 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-04  9:03 where/how 2nd kernel's elfcorehdr_addr comes from lizhijian
2022-11-05  1:38 ` lizhijian
2022-11-05  1:49 ` Baoquan He [this message]

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