linux-kernel - [PATCH] x86/apic: Replace the redundant macros with an empty stub

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Date:   Wed, 17 Jan 2018 15:37:48 +0800
From:   Dou Liyang <douly.fnst@...fujitsu.com>
To:     <linux-kernel@...r.kernel.org>, <x86@...nel.org>
CC:     <tglx@...utronix.de>, <mingo@...hat.com>, <hpa@...or.com>,
        <ville.syrjala@...ux.intel.com>, <mroos@...ux.ee>,
        Dou Liyang <douly.fnst@...fujitsu.com>
Subject: [PATCH] x86/apic: Replace the redundant macros with an empty stub

The X86_LOCAL_APIC is depended on CONFIG X86_64, that means if
CONFIG_X86_64=y, the X86_LOCAL_APIC must be y too.

So, using

  if defined(CONFIG_X86_64) || defined(CONFIG_X86_LOCAL_APIC)

... is redundant.

Remove the redundant macros and add an empty stub instead. also add some
comments for init_bsp_APIC().

Signed-off-by: Dou Liyang <douly.fnst@...fujitsu.com>
---
 arch/x86/include/asm/apic.h | 1 +
 arch/x86/kernel/irqinit.c   | 9 +++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 98722773391d..6e1990d69865 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -183,6 +183,7 @@ static inline void disable_local_APIC(void) { }
 # define setup_boot_APIC_clock x86_init_noop
 # define setup_secondary_APIC_clock x86_init_noop
 static inline void lapic_update_tsc_freq(void) { }
+static inline void init_bsp_APIC(void) { }
 static inline void apic_intr_mode_init(void) { }
 static inline void lapic_assign_system_vectors(void) { }
 static inline void lapic_assign_legacy_vector(unsigned int i, bool r) { }
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index a539410c4ea9..a0e41397558e 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 setup the through-local-APIC virtual wire mode earlier.
+	 *
+	 * In some 32bit UP machines whose APIC has been disabled by BIOS
+	 * and 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++)
-- 
2.14.3