Re: turning off APIC

[Mikael Pettersson]

On Sun, 15 Sep 2002 14:28:44 +0300, Andriy Rysin wrote:
>If APIC is compiled in the kernel (wich is the case with most 
>distributions) when I start kernel with "noapic" option, APIC is getting 
>enabled anyway and only later gets disabled. This causes problems on 
>some VAIO notebooks - it seems like BIOS gets confused if APIC was 
>turned on (particularly on my laptop when I try to reboot from Linux it 
>hangs saying that thera problems with keyboard). That would be much 
>better to have an option to turn it off in the boot options and not to 
>recompile the kernel. Could somebody comment this please?
>Please CC me on this email address.

Which APIC? local or I/O? Please be specific.
"noapic" does not and never has had anything to do with the
local APIC, only the I/O APIC. There is currently no kernel
option for preventing the local APIC from being enabled if
the kernel was built with local APIC support.

You have four options:
1. Recompile with CONFIG_SMP=n and CONFIG_X86_LOCAL_APIC=n.
2. Run dmidecode on your Vaio, dig out the identification strings,
   and add them to arch/i386/kernel/dmi_scan.c's local APIC
   blacklist.
3. Add a __setup in arch/i386/kernel/apic.c after the declaration
   for dont_enable_local_apic, which sets it to 1.
4. Tell Sony to fix the Vaio's BIOS.

/Mikael