Re: [discuss] [PATCH] add and handle NMI_VECTOR II

["Jan Beulich" <JBeulich@novell.com>]

>Index: linux/include/asm-x86_64/hw_irq.h
>===================================================================
>--- linux.orig/include/asm-x86_64/hw_irq.h
>+++ linux/include/asm-x86_64/hw_irq.h
>@@ -52,7 +52,7 @@ struct hw_interrupt_type;
> #define ERROR_APIC_VECTOR	0xfe
> #define RESCHEDULE_VECTOR	0xfd
> #define CALL_FUNCTION_VECTOR	0xfc
>-#define KDB_VECTOR		0xfb	/* reserved for KDB */
>+#define NMI_VECTOR		0xfb	/* IPI NMIs for debugging */
> #define THERMAL_APIC_VECTOR	0xfa
> /* 0xf9 free */
> #define INVALIDATE_TLB_VECTOR_END	0xf8

This doesn't seem too good an idea: the NMI vector really is 0x02
(architecturally), so defining it to something else seems at least odd.

>Index: linux/arch/x86_64/kernel/traps.c
>===================================================================
>--- linux.orig/arch/x86_64/kernel/traps.c
>+++ linux/arch/x86_64/kernel/traps.c
>@@ -931,7 +931,7 @@ void __init trap_init(void)
> 	set_system_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
> #endif
>        
>-	set_intr_gate(KDB_VECTOR, call_debug);
>+	set_intr_gate(NMI_VECTOR, call_debug);
>        
> 	/*
> 	 * Should be a barrier for any external CPU state.

I never understood what this does. If you deliver the IPI as an NMI,
it'll never arrive at this vector, and why would anyone want to put an
"int $NMI_VECTOR" anywhere?

Jan
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