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authorDou Liyang <douly.fnst@cn.fujitsu.com>2018-01-17 15:37:48 +0800
committerIngo Molnar <mingo@kernel.org>2018-02-13 17:30:38 +0100
commitccf5355d05cd891522267f04b2723002e7f061de (patch)
tree37a5cc39dd9535f5de34b12d1a6cd204afdf38ab /arch/x86/kernel/irqinit.c
parentafed7d172091040f38c75a2927fed170ea11585f (diff)
downloadlinux-ccf5355d05cd891522267f04b2723002e7f061de.tar.gz
x86/apic: Simplify init_bsp_APIC() usage
Since CONFIG_X86_64 selects CONFIG_X86_LOCAL_APIC, the following
condition:

  #if defined(CONFIG_X86_64) || defined(CONFIG_X86_LOCAL_APIC)

is equivalent to:

  #if defined(CONFIG_X86_LOCAL_APIC)

... and we can eliminate that #ifdef by providing an empty
init_bsp_APIC() stub in the !CONFIG_X86_LOCAL_APIC case.

Also add some comments to explain why we call init_bsp_APIC().

Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mroos@linux.ee
Cc: ville.syrjala@linux.intel.com
Link: http://lkml.kernel.org/r/20180117073748.23905-1-douly.fnst@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/irqinit.c')
-rw-r--r--arch/x86/kernel/irqinit.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index a539410c4ea9..772196c1b8c4 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -61,9 +61,14 @@ void __init init_ISA_irqs(void)
 	struct irq_chip *chip = legacy_pic->chip;
 	int i;
 
-#if defined(CONFIG_X86_64) || defined(CONFIG_X86_LOCAL_APIC)
+	/*
+	 * Try to set up the through-local-APIC virtual wire mode earlier.
+	 *
+	 * On some 32-bit UP machines, whose APIC has been disabled by BIOS
+	 * and then got re-enabled by "lapic", it hangs at boot time without this.
+	 */
 	init_bsp_APIC();
-#endif
+
 	legacy_pic->init(0);
 
 	for (i = 0; i < nr_legacy_irqs(); i++)