commit d654c673d6394bc26e159b1057b357371b4ce1dc
author Arjan van de Ven <arjan@linux.intel.com> Wed Nov 08 17:44:37 2006 -0800
committer Linus Torvalds <torvalds@g5.osdl.org> Wed Nov 08 18:29:22 2006 -0800
tree 1b1a4d13407a5bc2c773745a0d04eb0b37af8123
parent 082f2f84be5db164280483efa7eb1549d867353d

[PATCH] Regression in 2.6.19-rc microcode driver

If the microcode driver is built in (rather than module) there are some,
ehm, interesting effects happening due to the new "call out to userspace"
behavior that is introduced..  and which runs too early.  The result is a
boot hang; which is really nasty.

The patch below is a minimally safe patch to fix this regression for 2.6.19
by just not requesting actual microcode updates during early boot.  (That
is a good idea in general anyway)

The "real" fix is a lot more complex given the entire cpu hotplug scenario
(during cpu hotplug you normally need to load the microcode as well); but
the interactions for that are just really messy at this point; this fix at
least makes it work and avoids a full detangle of hotplug.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/kernel/microcode.c

diff --git a/arch/i386/kernel/microcode.c b/arch/i386/kernel/microcode.c
index c4d0291..23f5984 100644
--- a/arch/i386/kernel/microcode.c
+++ b/arch/i386/kernel/microcode.c
@@ -577,7 +577,7 @@
 	set_cpus_allowed(current, cpumask_of_cpu(cpu));
 	mutex_lock(&microcode_mutex);
 	collect_cpu_info(cpu);
-	if (uci->valid)
+	if (uci->valid && system_state == SYSTEM_RUNNING)
 		cpu_request_microcode(cpu);
 	mutex_unlock(&microcode_mutex);
 	set_cpus_allowed(current, old);