From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Shakthi Kannan <shakthimaan@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: CRC calculation in Module.symvers
Date: Wed, 7 Sep 2011 15:46:32 -0700 [thread overview]
Message-ID: <20110907224632.GE4387@linux.vnet.ibm.com> (raw)
In-Reply-To: <CABG-yt0t0sgAvcDDLhjyNFGpY22tL0CtDvXV9+CxYJMf0MdVfA@mail.gmail.com>
On Wed, Sep 07, 2011 at 11:28:46AM +0530, Shakthi Kannan wrote:
> Greetings!
>
> I would like to know as to:
>
> 1. How the CRC is computed for an exported symbol present in
> Module.symvers file, and
> 2. Given a kernel .c file, how can I obtain the CRC checksums for a symbol.
>
> For linux-3.0.2 (example), I compiled with CONFIG_MODVERSIONS=y, and
> running 'make' built vmlinux, and generated the Module.symvers file. I
> believe genksyms is used to create the Module.symvers file?
>
> I had referred the "Kernel Symbols and CONFIG_MODVERSIONS"
> documentation [1] written by Mark McLoughlin. I tried the following in
> the top-level kernel sources:
>
> $ gcc -E -D__GENKSYMS__ -DCONFIG_MODVERSIONS -DEXPORT_SYMTAB
> crypto/api.c -I/tmp/linux-3.0.2/include
> -I/tmp/linux-3.0.2/arch/x86/include | ./scripts/genksyms/genksyms
>
> and I get the following error output:
>
> === Output ===
>
> /tmp/linux-3.0.2/include/linux/jiffies.h:43:42: error: division by zero in #if
> In file included from /tmp/linux-3.0.2/include/linux/tracepoint.h:19:0,
> from /tmp/linux-3.0.2/include/linux/module.h:18,
> from crypto/api.c:22:
> /tmp/linux-3.0.2/include/linux/rcupdate.h:160:2: error: #error
> "Unknown RCU implementation specified to kernel configuration"
The above error message is emitted if none of CONFIG_TINY_RCU,
CONFIG_TINY_PREEMPT_RCU, CONFIG_TREE_RCU, and CONFIG_TREE_PREEMPT_RCU
is defined. Given that these four are in a "choice", I suspect that
you have broken the kernel build pretty impressively.
Thanx, Paul
> In file included from /tmp/linux-3.0.2/include/linux/module.h:21:0,
> from crypto/api.c:22:
> /tmp/linux-3.0.2/arch/x86/include/asm/module.h:59:2: error: #error
> unknown processor family
>
> === End ===
>
> The documentation for genksyms is old, and now there is no -k option?
>
> Appreciate any inputs in this regard,
>
> Thanks!
>
> SK
>
> [1] Kernel Symbols and CONFIG_MODVERSIONS.
> http://www.skynet.ie/~mark/pub/symbols.txt
>
> --
> Shakthi Kannan
> http://www.shakthimaan.com
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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> More majordomo info at http://vger.kernel.org/majordomo-info.html
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next prev parent reply other threads:[~2011-09-07 22:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-07 5:58 CRC calculation in Module.symvers Shakthi Kannan
2011-09-07 12:54 ` Michal Marek
2011-09-09 4:50 ` Shakthi Kannan
2011-09-09 13:17 ` Michal Marek
2011-09-10 2:55 ` Shakthi Kannan
2011-09-07 22:46 ` Paul E. McKenney [this message]
-- strict thread matches above, loose matches on Subject: below --
2011-09-06 7:11 Shakthi Kannan
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