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SubjectRe: "Latitude with broken BIOS" ?
Mikael Pettersson wrote:

> On Mon, 20 Jan 2003 04:31:58 -0800 (GMT-08:00), Alessandro Suardi wrote:
> > I was hoping to use HT on my new Latitude C640 (P4 @ 1.8Ghz) but at boot
> > both 2.4.21-pre3 and 2.5.59 (obviously with a SMP kernel) tell me
> >
> > "Dell Latitude with broken BIOS detected. Refusing to enable the local APIC."
> >
> > Is this anything that can be played with ?
>
> First of all, your 1.8GHz mobile P4 doesn't actually have HT.
> The only ones to have it are the new 3.06GHz P4s, and most Xeons.

Ok.

> Secondly, I'm responsible for the message you quoted. Many if not all
> Pentium III-based Dell laptops (including Latitude Cnnn and I8nnn)
> that have local-APIC capable processors fail miserably if the OS
> actually enables it. For instance, pulling or inserting the DC
> power plug would hang the machine. This is a BIOS bug we can't work
> around, except by refusing to enable the local APIC.
>
> Your P4-based Latitude probably has a different BIOS than the buggy
> P3-based ones, and it may work better. Try commenting out the
> local_apic_kills_bios entry for "Dell Latitude" at around line 692
> in arch/i386/kernel/dmi_scan.c and rebuild the kernel. If it

(ahem) I had tried that in 2.5.58 already ;)

However I rebuilt 2.5.59 with that change, and I'm not going further:

No local APIC present or hardware disabled

I have both CONFIG_X86_IO_APIC and CONFIG_X86_LOCAL_APIC=y.

(while I'm using my old PIII/750 the PIV is still okay for testing ;)


Ciao,

--alessandro
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