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

From: Jiang Liu
Date: Tue Jan 20 2015 - 20:50:31 EST


On 2015/1/16 19:05, Thomas Gleixner wrote:
> 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@xxxxxxxxxxxxx>
> 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@xxxxxxxxxxxxx>
> ---
> 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
Hi Thomas,
With above patch applied, it just gives a blank screen
instead of a panic when booting on my problematic laptop.
Now I have found the root cause of the failure on my laptop.
On i386, it triggers BUG_ON(!apic->apic_id_registered())
in function setup_local_APIC() because apic_bsp_up_setup() is called
too late. So we need a simple patch as below. With following patch
applied, it boots successfully with your original patch.
Regards,
Gerry
--------------------------------------------------------------------
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 6f3067807376..791148864a48 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2245,10 +2245,9 @@ int __init apic_bsp_setup(bool upmode)
int id;

connect_bsp_APIC();
- setup_local_APIC();
-
if (upmode)
apic_bsp_up_setup();
+ setup_local_APIC();

if (x2apic_mode)
id = apic_read(APIC_LDR);
---------------------------------------------------------------------
>
>
>
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