Updating the HAL for Multiprocessor support

[hedrums]

I thought I'd post this here in case it ever helps anyone else trying to do this.

A while back, I bought an AMD Opteron 185 dual-core to replace my beloved Fx-55. I do a fair amount of 3D rendering and those programs are often multi-processor friendly. I have a dual-boot system: XP and Vista Ultimate x64. Unsurprisingly, Vista saw both cores on the next boot after the processor install. XP did not.

XP just wouldn't see the other core (though ironically it would show two processors in the Device Manager, but it would report only one during boot and only ever use one core). It seems that when I installed XP, it picked a HAL that didn't offer MP in the Device Manager, so just changing that and rebooting was not an option. I found forums describing how sysprep could be used for this purpose, and after one such attempt and an un-bootable system, I abandoned that approach.

Microsoft even has a KB article telling you "you can't get there from here." They suggest reinstalling Windows XP. Sigh. Rather not, thanks...

And so it was for several weeks: XP using one core, Vista using both.

Then, finally, I found that the Microsoft tool devcon (Device Console) allows one to do all sorts of nasty things to the HAL, including changing it to support MP. There's also an MSDN page on how to do exactly what I was trying to do (in complete contradiction to the KB article that tells you it can't be done).

Anyway, here are the two lines that changed my HAL so I could use both cores:

devcon sethwid @ROOT\ACPI_HAL\0000 := +acpiapic_mp !acpiapic_up
devcon update c:\windows\inf\hal.inf acpiapic_mp.

Then reboot. Twice (one extra after XP does some contemplating).

That's it... now I have both processors available in XP and Vista.

The MSDN page telling how to do it is here:
http://msdn2.microsoft.com/en-us/library/ms792832.aspx#b47b84d3-6178-447c-ac60-aaeb017e5fc7

The relevant MS KB are:
http://support.microsoft.com/kb/299340/
and
http://support.microsoft.com/kb/309283/

For the record, mine was "Advanced Configuration and Power Interface (ACPI) PC", ACPI PIC HAL (Halacpi.dll)
... which, as you can see from the second KB article, doesn't support MPs.

Anyway, hopefully having this here may save someone the trouble of tracking down this incredibly simple approach again.

[squall_leonhart69r]

and did it update the HAL to the multi/uniprocessor supporting ACPI?

just had an idea.. this would enable APIC without requiring a repair install i think :\

edit
yup

i just converted from PIC to APIC without reinstalling windows

[TwL]

Thats cool.. Been checking out quite many places for this one.. I knew it's possible somehow but damn.. nice work mate..

[squall_leonhart69r]

i've gone back to PIC... apic put my video and sound card to 19 and 18 respectively and it pressing buttons on the keyboard quickly would cause sound lag (IRQ's are rated by priority.. IRQ 1 is highest and 22 is lowest.)

[hedrums]

Yes, it did update the HAL to the MP ACPI HAL. Took about five seconds.

And yes, it should enable APIC without a repair install (assuming your hardware supports it, and nearly everything does these days) -- and I see that it did work for you (excellent).

I didn't have to install or repair anything -- just rebooted twice (the first time XP says, "oh, you have some new stuff... give me a minute") and I was done. I couldn't believe how easy it was when I finally found the answer!

As always, back up everything you care about first, just in case.

[squall_leonhart69r]

i went to apic, and went back.

it put my sound card and video card on too high an IRQ and it was causing audio stuttering when i pressed or held buttons on the keyboard

[Seawolf]

That's really screwy. APIC is far more efficient, so that should never happen unless you have some really bad hardware or drivers.

[sneakypete]

I tried these steps under vista and the 2nd one fails!

Here is the input/output from my prompt:
c:\devcon sethwid @ROOT\ACPI_HAL\0000 := +acp
iapic_mp !acpiapic_up
ROOT\ACPI_HAL\0000 : acpiapic_mp,acpiap
ic
Modified 1 hardware ID(s).

c:\devcon update c:\windows\inf\hal.inf acpia
pic_mp.
Updating drivers for acpiapic_mp. from c:\windows\inf\hal.inf.
devcon failed.

Anyone figured out how to do this in Vista?

[squall_leonhart69r]

That's really screwy. APIC is far more efficient, so that should never happen unless you have some really bad hardware or drivers.

no, it does happen, quite a lot in fact, and it has nothing to do with drivers.

[sneakypete]

http://www.planetamd64.com/lofiversion/ ... 30279.html