linux-kernel - Re: [BUG] i386 relocable kernel breakes /proc/kcore debugging

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Message-ID: <m1fy39thjz.fsf@ebiederm.dsl.xmission.com>
Date:	Fri, 27 Jul 2007 19:58:56 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Maxim Levitsky <maximlevitsky@...il.com>
Cc:	linux-kernel@...r.kernel.org, Vivek Goyal <vgoyal@...ibm.com>,
	Kexec Mailing List <kexec@...ts.infradead.org>
Subject: Re: [BUG] i386 relocable kernel breakes /proc/kcore debugging

Maxim Levitsky <maximlevitsky@...il.com> writes:

> Hello,
>
> Today I noticed that gdb gets confused when I try to load a vmlinux image.
> gdb 'thinks' that all kernel symbols are below 0x80000000 , while they are at 
> 0xC000....
>
> Turning CONFIG_RELOCATABLE off fixes that, so I assume that is the reason for 
> that.
>
> I am using 2.6.23-rc1, although I don't think that older versions are better.
>
> Best regards,
> 	Maxim Levitsky

Weird.

Vivek could this be related to the problem of problematic core dumps we
were seeing earlier?

Eric


> PS: 
> This is what gdb says:

>
> (gdb) disassemble sys_open
> Dump of assembler code for function sys_open:
> 0x8026fa60 <sys_open+0>:        Cannot access memory at address 0x8026fa60
>
> While real address of sys_open is:
>
> [root@...N linux-2.6]# nm ./.obj/vmlinux |  grep sys_open
> .........
> c016ea60 T sys_open
>
> Strange, but gdb recordnizes the above address directly:
>
> (gdb) disassemble 0xc016ea60
> Dump of assembler code for function sys_open:
> 0xc016ea60 <sys_open+0>:        sub    $0x4,%esp
> 0xc016ea63 <sys_open+3>:        mov    0x10(%esp),%eax
> ...............
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