Re: [Trion-kernel-dev] Compatibility patch

[Daniel R. <cos...@gm...>]

Hello Manuel
thanks for the test-run.. Good to see that it also works on the more dated  
hardware.

> There it is again (the version 03).  I guess it's legitimate.

Either that or you two just happen to use mainboards with the same chipset  
;). From what I can tell versions numbers 0x01 through 0x10 are reserved  
for I/O APICs of the 486 era that didn't yet use the new APIC architecture  
(XAPIC). Here's a snipped of the linux code that checks the version number  
at boot-time:

if((reg_01.bits.version != 0x01) && /* 82489DX IO-APICs      */
    (reg_01.bits.version != 0x10) && /* oldest IO-APICs       */
    (reg_01.bits.version != 0x11) && /* Pentium/Pro IO-APICs  */
    (reg_01.bits.version != 0x13) && /* Xeon IO-APICs         */
    (reg_01.bits.version != 0x20))   /* Intel P64H (82806 AA) */
{
     UNEXPECTED_IO_APIC();
}

I propably should add that UNEXPECTED_IO_APIC() is just some empty stub  
procedure, so that the kernel still boots if the version is other than the  
expected values.

regards,
cosmo86

http://lxr.linux.no/source/arch/i386/kernel/io_apic.c#L1302