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Date: Sat, 27 Apr 2013 23:53:36 +0300
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Subject: Re: config(8) -x headscratcher
From: Kimmo Paasiala <kpaasial@gmail.com>
To: "Wojciech A. Koszek" <wkoszek@freebsd.org>
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On Sat, Apr 27, 2013 at 11:42 PM, Kimmo Paasiala <kpaasial@gmail.com> wrote:
> On Sat, Apr 27, 2013 at 10:05 PM, Wojciech A. Koszek
> <wkoszek@freebsd.org> wrote:
>> On Sat, Apr 27, 2013 at 06:54:11PM +0300, Kimmo Paasiala wrote:
>>> I'm getting a core dump on 'config -x /boot/kernel/kernel' on 9.1-RELEASE i386.
>>>
>>> Assertion failed: (r != '\0' && ("Char present in the configuration "
>>> "string mustn't be equal to 0")), function kernconfdump, file
>>> /usr/src/usr.sbin/config/main.c, line 710.
>>>
>>> I have double checked that my config file is sane and does not have
>>> any funny characters anywhere.
>>>
>>> The system is i386 9.1-RELEASE r249856. The world and kernel are built
>>> with clang and I'm suspecting that the use of clang has something to
>>> do with this segfault.
>>>
>>> Looking at the kernel files I can see one very obvious difference.
>>> This is the 'elfdump -c kernel | grep -A 8 kern_conf' output (what
>>> config -x seems to use for finding out the config file from the kernel
>>> image) for the GENERIC kernel from the stock installation:
>>>
>>> sh_name: kern_conf
>>> sh_type: SHT_PROGBITS
>>> sh_flags: SHF_ALLOC
>>> sh_addr: 0xc1039f80
>>> sh_offset: 12820352
>>> sh_size: 3771
>>> sh_link: 0
>>> sh_info: 0
>>> sh_addralign: 32
>>>
>>> And this is from the kernel I have built myself using clang and a
>>> custom config file:
>>>
>>> sh_name: kern_conf
>>> sh_type: SHT_PROGBITS
>>> sh_flags: SHF_ALLOC
>>> sh_addr: 0xc09aee9c
>>> sh_offset: 5959324
>>> sh_size: 1994
>>> sh_link: 0
>>> sh_info: 0
>>> sh_addralign: 1
>>>
>>> The align field looks suspicious, config -x seems to use it to check
>>> for padding but to me it looks like the logic may not work if the
>>> alignment is 1.
>>>
>>> This the relevant bit from main.c of config(8)
>>>
>>
>> Kimmo,
>>
>> Lets keep discussion on hackers@ only. I do agree with you that config(8)
>> internal implementation might have its issues.
>>
>> Can you make your kernel configuration file, faulty kernel image and exact
>> build instructions available to me?
>>
>> --
>> Wojciech A. Koszek
>> wkoszek@FreeBSD.czest.pl
>> http://FreeBSD.czest.pl/~wkoszek/
>
> The kernel config file:
>
> http://pastebin.com/j0J9NPCi
>
> My /etc/make.conf:
>
> http://pastebin.com/HYudWCA9
>
> And /etc/src.conf:
>
> http://pastebin.com/ZAKq6ABT
>
> I'll see how I can make the kernel image available.
>
> -Kimmo
The kernel file:
https://www.dropbox.com/s/07mjk6j4ditbl9r/kernel
-Kimmo