How to update the HAL without reinstalling windows

Heres some tips for upgraders!

You require the Devcon utility for this, unpack it to a folder, then navigate to the folder its in using Command prompt (command prompt on context menu PowerToy is handy for this)

How to enable APIC without repair installing windows
in device manager you will notice that under computer type it says Advanced Power and Control Interface PC.. this is a standard single processor HAL driver without APIC. to upgrade to the APIC driver you input the following:

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

after this, enable APIC in the bios if you haven't already, and reboot twice so windows can update the device and irq tables, it should now say ACPI Uniprocessor PC in the device manager


How to go back to PIC
if you wish to go back to PIC from APIC enter this:

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

and reboot twice to update the device and IRQ tables, and then disable APIC in the bios (the reason is, if you disable APIC before the device and irq tables update, windows will crash at startup.

How to Update from a Single Core APIC compatible cpu to a Multicore APIC compatible cpu

under the computer entry in the device manager, you will see it says ACPI Uniprocessor PC, to update to the multiprocessor HAL input this:

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

Then reboot twice again to update the device and IRQ tables.

How to go back to Single Core (should it be needed)
if you accidentally burn your processor and have to go back to a single core backup, you input this into the devcon:

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

and always reboot twice.

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