linux-kernel - Re: [Suggestion] about calling debug_hotplug_cpu() which enabled by 'allmodconfig' for a x86

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Date:	Fri, 04 Oct 2013 17:27:47 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Toshi Kani <toshi.kani@...com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	"rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
	"isimatu.yasuaki@...fujitsu.com" <isimatu.yasuaki@...fujitsu.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [Suggestion] about calling debug_hotplug_cpu() which enabled
 by 'allmodconfig' for a x86_64 dual core laptop.

On 10/03/2013 11:07 PM, Toshi Kani wrote:
> On Thu, 2013-10-03 at 22:21 +0800, Chen Gang wrote:
>> One root cause found (but not only one), allmodconfig will enable
>> CONFIG_SYSFS_DEPRECATED which for new kernel on old distribution.
>>
>>
>> I am comparing from allmodconfig config file to defconfig config file,
>> the attachments are middle files (one enable CONFIG_SYSFS_DEPRECATED
>> which can not boot up, the other disable it which can boot up).
>>
>> The related information in "init/Kconfig"
>>
>>   config SYSFS_DEPRECATED
>>     bool "Enable deprecated sysfs features to support old userspace tools"
>>     depends on SYSFS
>>     default n
>>     help
>>       This option adds code that switches the layout of the "block" class
>>       devices, to not show up in /sys/class/block/, but only in
>>       /sys/block/.
>>
>>       This switch is only active when the sysfs.deprecated=1 boot option is
>>       passed or the SYSFS_DEPRECATED_V2 option is set.
>>
>>       This option allows new kernels to run on old distributions and tools,
>>       which might get confused by /sys/class/block/. Since 2007/2008 all
>>       major distributions and tools handle this just fine.
>>
>>       Recent distributions and userspace tools after 2009/2010 depend on
>>       the existence of /sys/class/block/, and will not work with this
>>       option enabled.
>>
>>       Only if you are using a new kernel on an old distribution, you might
>>       need to say Y here.
>>
>>
>> I will continue to analyze another related issues for allmodconfig on
>> my laptop (after disable SYSFS_DEPRECATED, for allmodconfig, it still
>> can not boot up successfully, although my 'middle' config file can).
> 
> Since this is no longer a hotplug issue, I'd suggest you change the
> subject line and resend it to the folks who worked on this config
> option.  I won't be able to help on this one.
> 

OK, thanks, I will/should send related information (or patch) to the
related members for continue discussing.

And again, thank you for spending your time on it (already provided
useful information)

:-)

> -Toshi
> 
> 
> 
> 

Thanks.
-- 
Chen Gang
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