linux-kernel - Re: [PATCH] libkmod-elf: resolve CRC if module is built with MODULE_REL

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Date:   Wed, 19 Jul 2017 22:04:19 +0300
From:   Yauheni Kaliuta <yauheni.kaliuta@...hat.com>
To:     Lucas De Marchi <lucas.de.marchi@...il.com>
Cc:     linux-modules <linux-modules@...r.kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] libkmod-elf: resolve CRC if module is built with MODULE_REL_CRCS

Hi, Lucas!

>>>>> On Wed, 19 Jul 2017 10:51:44 -0700, Lucas De Marchi  wrote:
 > On Wed, Jul 19, 2017 at 7:56 AM, Yauheni Kaliuta
 > <yauheni.kaliuta@...hat.com> wrote:
 >> Normally exported symbol's crc is stored as absolute (SHN_ABS)
 >> value of special named symbol __crc_<symbol name>.
 >> 
 >> When the kernel and modules are built with the config option
 >> CONFIG_MODULE_REL_CRCS, all the CRCs are put in a special section
 >> and the __crc_<symbol name> symbols values are offsets in the
 >> section. See patch description of the commit:
 >> 
 >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=56067812d5b0e737ac2063e94a50f76b810d6ca3
 >> 
 >> Add kmod support of this configuration.

[...]

 > LGTM. I'll give this a try and apply.

Thanks! I would also like to get some feedback from the kernel feature
author, Ard Biesheuvel, that this does not miss other usecases.

 > Do you think it's possible to build an out-of-tree module with this
 > option so we can add one to the testsuite?

I'll check what I can do.

The problem is seen if you run depmod with -e -E, which I guess is not used
too often.

-- 
WBR,
Yauheni Kaliuta