Re: [patch 00/23] x86: Cleanup apic/ioapic/x2apic setup code

[Thomas Gleixner <tglx@linutronix.de>]

On Fri, 16 Jan 2015, Thomas Gleixner wrote:
> On Fri, 16 Jan 2015, Jiang Liu wrote:
> > 5) x86_32, UP, IO_APIC disabled
> > 5.1) boot: panic with following call stack:
> > do_ono_initcall()->APIC_init_uniprocessor()->setup_local_APIC().
> > I can't capture the full log message due to lack of serial console.
> > It seems we have trouble with:
> > early_initcall(APIC_init_uniprocessor);
> 
> Hmm, worked here. Lemme find some other machine.

Found the issue, won't work. But I still want to remove that x86
nonsense from init. So we need to do it different.

Subject: init: Get rid of x86isms
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 14 Jan 2015 14:59:48 +0100

Provide a config option and make the UP smp_init() implementation
depend on it and confine this to x86.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/Kconfig            |    4 ++++
 arch/x86/kernel/apic/apic.c |    7 +++++++
 include/linux/smp.h         |    6 ++++++
 init/main.c                 |   13 -------------
 4 files changed, 17 insertions(+), 13 deletions(-)

Index: tip/arch/x86/Kconfig
===================================================================
--- tip.orig/arch/x86/Kconfig
+++ tip/arch/x86/Kconfig
@@ -855,6 +855,10 @@ config SCHED_MC
 
 source "kernel/Kconfig.preempt"
 
+config UP_SMP_INIT
+       def_bool y
+       depends on X86_UP_APIC
+
 config X86_UP_APIC
 	bool "Local APIC support on uniprocessors"
 	depends on X86_32 && !SMP && !X86_32_NON_STANDARD && !PCI_MSI
Index: tip/arch/x86/kernel/apic/apic.c
===================================================================
--- tip.orig/arch/x86/kernel/apic/apic.c
+++ tip/arch/x86/kernel/apic/apic.c
@@ -2265,6 +2265,13 @@ int __init APIC_init_uniprocessor(void)
 	return 0;
 }
 
+#ifdef CONFIG_UP_SMP_INIT
+void smp_init(void)
+{
+	APIC_init_uniprocessor();
+}
+#endif
+
 /*
  * Power management
  */
Index: tip/include/linux/smp.h
===================================================================
--- tip.orig/include/linux/smp.h
+++ tip/include/linux/smp.h
@@ -151,6 +151,12 @@ smp_call_function_any(const struct cpuma
 static inline void kick_all_cpus_sync(void) {  }
 static inline void wake_up_all_idle_cpus(void) {  }
 
+#ifdef CONFIG_UP_SMP_INIT
+extern void __init smp_init(void);
+#else
+static inline void smp_init(void) { }
+#endif
+
 #endif /* !SMP */
 
 /*
Index: tip/init/main.c
===================================================================
--- tip.orig/init/main.c
+++ tip/init/main.c
@@ -87,10 +87,6 @@
 #include <asm/sections.h>
 #include <asm/cacheflush.h>
 
-#ifdef CONFIG_X86_LOCAL_APIC
-#include <asm/smp.h>
-#endif
-
 static int kernel_init(void *);
 
 extern void init_IRQ(void);
@@ -351,15 +347,6 @@ __setup("rdinit=", rdinit_setup);
 
 #ifndef CONFIG_SMP
 static const unsigned int setup_max_cpus = NR_CPUS;
-#ifdef CONFIG_X86_LOCAL_APIC
-static void __init smp_init(void)
-{
-	APIC_init_uniprocessor();
-}
-#else
-#define smp_init()	do { } while (0)
-#endif
-
 static inline void setup_nr_cpu_ids(void) { }
 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 #endif