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Re: [PATCH v2 4/4] dynamic_debug: add jump label support

From Jason Baron <jbaron@akamai.com>
Newsgroups linux.kernel
Subject Re: [PATCH v2 4/4] dynamic_debug: add jump label support
Date 2016-06-10 17:40 +0200
Message-ID <rIwHo-6kc-3@gated-at.bofh.it> (permalink)
References <rAZZT-2CA-5@gated-at.bofh.it> <rAZZT-2CA-9@gated-at.bofh.it> <rIrol-2W0-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 06/10/2016 05:54 AM, Arnd Bergmann wrote:
> On Friday, May 20, 2016 5:16:36 PM CEST Jason Baron wrote:
>> Although dynamic debug is often only used for debug builds, sometimes its
>> enabled for production builds as well. Minimize its impact by using jump
>> labels. This reduces the text section by 7000+ bytes in the kernel image
>> below. It does increase data, but this should only be referenced when
>> changing the direction of the branches, and hence usually not in cache.
>>
>>    text	   data	    bss	    dec	    hex	filename
>> 8194852	4879776	 925696	14000324	 d5a0c4	vmlinux.pre
>> 8187337	4960224	 925696	14073257	 d6bda9	vmlinux.post
>>
>> Signed-off-by: Jason Baron <jbaron@akamai.com>
>> ---
> 
> This causes problems for some of my randconfig builds, when a dynamic
> debug call is used inside of an __exit function:
> 
> `.exit.text' referenced in section `__jump_table' of drivers/built-in.o: defined in discarded section `.exit.text' of drivers/built-in.o
> `.exit.text' referenced in section `__jump_table' of drivers/built-in.o: defined in discarded section `.exit.text' of drivers/built-in.o
> 
> 	Arnd
> 

Hi,

I stuck pr_debug() in a few functions marked with __exit, but did not
reproduce yet. Can you share your .config and gcc --version.

Thanks,

-Jason

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Thread

Re: [PATCH v2 4/4] dynamic_debug: add jump label support Arnd Bergmann <arnd@arndb.de> - 2016-06-10 12:00 +0200
  Re: [PATCH v2 4/4] dynamic_debug: add jump label support Jason Baron <jbaron@akamai.com> - 2016-06-10 17:40 +0200
    Re: [PATCH v2 4/4] dynamic_debug: add jump label support Arnd Bergmann <arnd@arndb.de> - 2016-06-13 18:10 +0200
      Re: [PATCH v2 4/4] dynamic_debug: add jump label support Arnd Bergmann <arnd@arndb.de> - 2016-06-13 22:30 +0200
        Re: [PATCH v2 4/4] dynamic_debug: add jump label support Jason Baron <jbaron@akamai.com> - 2016-06-13 22:40 +0200
  Re: [PATCH v2 4/4] dynamic_debug: add jump label support Jason Baron <jbaron@akamai.com> - 2016-06-10 23:30 +0200

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