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Message-ID: <524E8A13.7020903@asianux.com>
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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