From d68921f9bd148359e6d01c84aaa2e32bfbd82970 Mon Sep 17 00:00:00 2001
From: Len Brown <len.brown@intel.com>
Date: Mon, 11 May 2015 17:27:09 -0400
Subject: x86/smp/boot: Add cmdline "cpu_init_udelay=N" to specify cpu_up()
 delay
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

No change to default behavior.

Replace the hard-coded mdelay(10) in cpu_up() with a variable
udelay, that is set to a defined default -- rather than a magic
number.

Add a boot-time override, "cpu_init_udelay=N"

Signed-off-by: Len Brown <len.brown@intel.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan H. Schönherr <jschoenh@amazon.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2fe8e6c798e8def271122f62df9bbf58dc283e2a.1431379433.git.len.brown@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 Documentation/kernel-parameters.txt | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'Documentation/kernel-parameters.txt')

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 61ab162..a320a41 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -746,6 +746,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 	cpuidle.off=1	[CPU_IDLE]
 			disable the cpuidle sub-system
 
+	cpu_init_udelay=N
+			[X86] Delay for N microsec between assert and de-assert
+			of APIC INIT to start processors.  This delay occurs
+			on every CPU online, such as boot, and resume from suspend.
+			Default: 10000
+
 	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
 			Format:
 			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
-- 
cgit v1.1