linux-kernel - Why BOOT_PRINTK_DELAY "may adversely affect SMP systems"?

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Message-ID: <4E9FE8C6.10402@gmail.com>
Date:	Thu, 20 Oct 2011 17:24:22 +0800
From:	snakky.zhang@...il.com
To:	linux-kernel@...r.kernel.org
Subject: Why BOOT_PRINTK_DELAY "may adversely affect SMP systems"?

Hi experts,

I noticed there is an kernel option called BOOT_PRINTK_DELAY and some
warning messages in the Kconfig file as below:

NOTE:  Using this option may adversely affect SMP systems. I.e.,
processors other than the first one may not boot up. BOOT_PRINTK_DELAY
also may cause DETECT_SOFTLOCKUP to detect what it believes to be lockup
conditions.

As my understanding, this do nothing but just let the very CPU loop for
a while and shouldn't cause any affect on the boot process. So I can
hardly understand WHY it may cause "processors other than the first one
may not boot up"? If this issue can be avoid/fixed?

Thanks a lot!
Snakky

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