From: Ingo Molnar <mingo@kernel.org>
Date: Wed, 13 May 2015 06:40:49 +0000 (+0200)
Subject: Revert f5d6a52f5111 ("x86/smpboot: Skip delays during SMP initialization similar... 
X-Git-Tag: omap-for-v4.2/fixes-rc1^2~170^2~26
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=853b160aaafbe27d6304c8832bb7340d57c6b04e;p=pandora-kernel.git

Revert f5d6a52f5111 ("x86/smpboot: Skip delays during SMP initialization similar to Xen")

Huang Ying reported x86 boot hangs due to this commit.

Turns out that the change, despite its changelog, does more
than just change timeouts: it also changes the way we
assert/deassert INIT via the APIC_DM_INIT IPI, in the x2apic
case it skips the deassert step.

This is historically fragile code and the patch did not
improve it, so revert these changes.

This commit:

  1a744cb356c5 ("x86/smp/boot: Remove 10ms delay from cpu_up() on modern processors")

independently removes the worst of the delays (the 10 msec delay).

The remaining delays can be addressed one by one, combined
with careful testing.

Reported-by: Huang Ying <ying.huang@intel.com>
Cc: Anthony Liguori <aliguori@amazon.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Gang Wei <gang.wei@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan H. Schönherr <jschoenh@amazon.de>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Deegan <tim@xen.org>
Link: http://lkml.kernel.org/r/1430732554-7294-1-git-send-email-jschoenh@amazon.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

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