linux-kernel - Re: [PATCH] - x86_64-add-ioapic-nmi-support-fix-3

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Message-ID: <468591F2.6050904@oracle.com>
Date:	Fri, 29 Jun 2007 16:12:50 -0700
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	John Keller <jpk@....com>
CC:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	steiner@....com
Subject: Re: [PATCH] - x86_64-add-ioapic-nmi-support-fix-3

[adding Andi Kleen]

John Keller wrote:
> Place all the IOACPI NMI support code under CONFIG_ACPI
> to clear up build errors with certain configs.
> 
> Signed-off-by: John Keller <jpk@....com>
> ---

Is there some architectural reason that IO APIC NMI support should
require ACPI?

Is this a new requirement?  It seems like a step backwards to me.


Documentation/nmi_watchdog.txt doesn't say anything about ACPI being
needed.  It does say:

"For x86-64, the needed APIC is always compiled in, and the NMI watchdog is
always enabled with I/O-APIC mode (nmi_watchdog=1). Currently, local APIC
mode (nmi_watchdog=2) does not work on x86-64.

Using local APIC (nmi_watchdog=2) needs the first performance register, so
you can't use it for other purposes (such as high precision performance
profiling.) However, at least oprofile and the perfctr driver disable the
local APIC NMI watchdog automatically."



>  arch/x86_64/kernel/io_apic.c |   77 +++++++++++++++++----------------
>  1 file changed, 40 insertions(+), 37 deletions(-)
> 
> 
> Index: linux-2.6.22-rc6/arch/x86_64/kernel/io_apic.c
> ===================================================================
> --- linux-2.6.22-rc6.orig/arch/x86_64/kernel/io_apic.c	2007-06-29 08:56:46.000000000 -0500
> +++ linux-2.6.22-rc6/arch/x86_64/kernel/io_apic.c	2007-06-29 10:28:08.109040333 -0500
> @@ -76,6 +76,10 @@ struct irq_cfg irq_cfg[NR_IRQS] __read_m
>  	[15] = { .domain = CPU_MASK_ALL, .vector = IRQ15_VECTOR, },
>  };
>  
> +#ifdef CONFIG_ACPI
> +static void setup_ioapic_nmi_irq(int ioapic, int pin,
> +				 struct IO_APIC_route_entry *entry);
> +#endif
>  static int assign_irq_vector(int irq, cpumask_t mask);
>  
>  #define __apicdebuginit  __init
> @@ -1168,9 +1172,6 @@ void __apicdebuginit print_PIC(void)
>  
>  #endif  /*  0  */
>  
> -static void setup_ioapic_nmi_irq(int ioapic, int pin,
> -				 struct IO_APIC_route_entry *entry);
> -
>  static void __init enable_IO_APIC(void)
>  {
>  	union IO_APIC_reg_01 reg_01;
> @@ -1211,8 +1212,10 @@ static void __init enable_IO_APIC(void)
>  				continue;
>  			}
>  
> +#ifdef CONFIG_ACPI
>  			if (entry.delivery_mode == dest_NMI)
>  				setup_ioapic_nmi_irq(apic, pin, &entry);
> +#endif
>  		}
>  	}
>  
> @@ -1586,40 +1589,6 @@ static void setup_nmi (void)
>  	printk(" done.\n");
>  }
>  
> -#define disable_nmi_ioapic      mask_IO_APIC_irq
> -#define enable_nmi_ioapic       unmask_IO_APIC_irq
> -
> -static struct irq_chip nmi_ioapic_chip __read_mostly = {
> -	.name		= "IO-APIC NMI",
> -	.enable		= enable_nmi_ioapic,
> -	.disable	= disable_nmi_ioapic,
> -	.mask		= mask_IO_APIC_irq,
> -	.unmask		= unmask_IO_APIC_irq,
> -};
> -
> -void __init setup_ioapic_nmi_irq(int apic, int pin,
> -				 struct IO_APIC_route_entry *entry)
> -{
> -	int irq;
> -
> -	entry->dest_mode = INT_DEST_MODE;
> -	entry->dest = cpu_mask_to_apicid(TARGET_CPUS);
> -	ioapic_write_entry(apic, pin, *entry);
> -
> -	irq = mp_apic_pin_to_gsi(apic, pin);
> -
> -	/* Setup pin_2_irq[irq] entry */
> -	add_pin_to_irq(irq, apic, pin);
> -
> -	irq_desc[irq].status = IRQ_NOREQUEST | IRQ_NO_BALANCING;
> -	if (!entry->mask) {
> -		irq_desc[irq].status &= ~IRQ_DISABLED;
> -		irq_desc[irq].depth = 0;
> -	}
> -
> -	set_irq_chip(irq, &nmi_ioapic_chip);
> -}
> -
>  /*
>   * This looks a bit hackish but it's about the only one way of sending
>   * a few INTA cycles to 8259As and any associated glue logic.  ICR does
> @@ -2282,6 +2251,40 @@ void __init io_apic_set_nmi_src_irq(int 
>  	ioapic_write_entry(ioapic, pin, entry);
>  }
>  
> +#define disable_nmi_ioapic      mask_IO_APIC_irq
> +#define enable_nmi_ioapic       unmask_IO_APIC_irq
> +
> +static struct irq_chip nmi_ioapic_chip __read_mostly = {
> +	.name		= "IO-APIC NMI",
> +	.enable		= enable_nmi_ioapic,
> +	.disable	= disable_nmi_ioapic,
> +	.mask		= mask_IO_APIC_irq,
> +	.unmask		= unmask_IO_APIC_irq,
> +};
> +
> +void __init setup_ioapic_nmi_irq(int apic, int pin,
> +				 struct IO_APIC_route_entry *entry)
> +{
> +	int irq;
> +
> +	entry->dest_mode = INT_DEST_MODE;
> +	entry->dest = cpu_mask_to_apicid(TARGET_CPUS);
> +	ioapic_write_entry(apic, pin, *entry);
> +
> +	irq = mp_apic_pin_to_gsi(apic, pin);
> +
> +	/* Setup pin_2_irq[irq] entry */
> +	add_pin_to_irq(irq, apic, pin);
> +
> +	irq_desc[irq].status = IRQ_NOREQUEST | IRQ_NO_BALANCING;
> +	if (!entry->mask) {
> +		irq_desc[irq].status &= ~IRQ_DISABLED;
> +		irq_desc[irq].depth = 0;
> +	}
> +
> +	set_irq_chip(irq, &nmi_ioapic_chip);
> +}
> +
>  #endif /* CONFIG_ACPI */
>  
>  


-- 
~Randy
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