ACPI disappears silently if !CONFIG_X86_LOCAL_APIC

ACPI disappears silently if !CONFIG_X86_LOCAL_APIC

[Dominik Brodowski]

On some systems where ACPI used to work fine, APIC support is not really 
needed in the kernel because the mobile chipset/processor doesn't support
it. Nonetheless, in 2.6.0-test3-bk-current, CONFIG_ACPI depends on
CONFIG_X86_LOCAL_APIC. As it's only a requirement for ACPI_HT, this patch
should be fine [it compiles and it works on my notebook].

	Dominik

--- linux-2.6.0-test3+2/drivers/acpi/Kconfig.original	2003-08-15 16:48:16.000000000 +0200
+++ linux-2.6.0-test3+2/drivers/acpi/Kconfig	2003-08-15 16:53:56.000000000 +0200
@@ -30,7 +30,7 @@
 	bool "Full ACPI Support"
 	depends on !X86_VISWS
 	depends on !IA64_HP_SIM
-	depends on IA64 || (X86 && ACPI_HT)
+	depends on IA64 || (X86 && ACPI_HT) || (X86 && !X86_LOCAL_APIC)
 	default y
 	---help---
 	  Advanced Configuration and Power Interface (ACPI) support for 


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RE: ACPI disappears silently if !CONFIG_X86_LOCAL_APIC

[Brown, Len]

Dominik,
I think your patch is correct, and I'll include it in my next update.

CONFIG_ACPI_HT, as you can see, is really just an alias for
CONFIG_ACPI_BOOT.  It is necessary, but not suficient to enable HT.
CONFIG_SMP is also needed to enable > 1 processor, and it will bring
with it CONFIG_X86_LOCAL_APIC -- so CONFIG_ACPI_HT doesn't need to
depend on it -- and it should be possible to exclude LAPIC code and
still run ACPI.

Thanks for the catch.

-Len

Ps.
Does your laptop really have no LAPIC, or you just prefer to not use
LAPIC?
Note that even if the system has no IOAPIC, the LAPIC is used for timer
interrupts.  On a laptop w/o IOAPIC, you'd see this in the boot
messages:

Found and enabled local APIC!
...
Using local APIC timer interrupts.
calibrating APIC timer ...

> -----Original Message-----
> From: Dominik Brodowski [mailto:linux-JhLEnvuH02M@public.gmane.org] 
> Sent: Friday, August 15, 2003 11:34 AM
> To: acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org; Grover, Andrew
> Subject: [ACPI] ACPI disappears silently if !CONFIG_X86_LOCAL_APIC
> 
> 
> On some systems where ACPI used to work fine, APIC support is 
> not really 
> needed in the kernel because the mobile chipset/processor 
> doesn't support
> it. Nonetheless, in 2.6.0-test3-bk-current, CONFIG_ACPI depends on
> CONFIG_X86_LOCAL_APIC. As it's only a requirement for 
> ACPI_HT, this patch
> should be fine [it compiles and it works on my notebook].
> 
> 	Dominik
> 
> --- linux-2.6.0-test3+2/drivers/acpi/Kconfig.original	
> 2003-08-15 16:48:16.000000000 +0200
> +++ linux-2.6.0-test3+2/drivers/acpi/Kconfig	2003-08-15 
> 16:53:56.000000000 +0200
> @@ -30,7 +30,7 @@
>  	bool "Full ACPI Support"
>  	depends on !X86_VISWS
>  	depends on !IA64_HP_SIM
> -	depends on IA64 || (X86 && ACPI_HT)
> +	depends on IA64 || (X86 && ACPI_HT) || (X86 && !X86_LOCAL_APIC)
>  	default y
>  	---help---
>  	  Advanced Configuration and Power Interface (ACPI) support for 
> 
> 
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RE: ACPI disappears silently if !CONFIG_X86_LOCAL_APIC

[Brown, Len]

> I think your patch is correct

I should note that I applied slightly different syntax -- removed
X86_LOCAL_APIC from acpi/Kconfig althgether.

Cheers,
-Len


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Re: ACPI disappears silently if !CONFIG_X86_LOCAL_APIC

[Bas Mevissen]

Brown, Len wrote:

> Ps.
> Does your laptop really have no LAPIC, or you just prefer to not use
> LAPIC?
> Note that even if the system has no IOAPIC, the LAPIC is used for timer
> interrupts.  On a laptop w/o IOAPIC, you'd see this in the boot
> messages:
> 

Is it a problem to have the local APIC support not compiled into the kernel?

What if the kernel refuses to enable local APIC because of a a broken 
BIOS report (or something like that, forgot the exact message). It that 
fixable with the DSDT or something else?

Regards,

Bas.





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