HAL in XP, does it automatically adapt for CPU change?

harrowc used Ask the Experts™
If installing XP on a uniprocessor system, is the HAL, by default, ACPI Multiprocessor or Uniprocessor?

If I install with one CPU (single core) and then later change CPU to a dual-core, will the HAL automatically adjust to cater for ACPI Multiprocessing support?

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As far as the default HAL is concerned... I am not sure, after having a quick read online, I reckon it depends on the type of cpu that is installed at windows installation time. This link seems to have good info on the HAL generally.


I am not sure about whether the HAL changes automatically, but I have a knowledge base article from microsoft that may be of assistance in changing the HAL manually.


Hope you find this information helpful



This part of the KB answers the question:

'On Windows XP and later versions, the ACPI Uniprocessor HAL and the MPS Uniprocessor HAL recognize the existence of more than one processor and report the MP ID. Plug and Play detects that the computer devnode's hardware ID list has changed and moves the devnode back through the "found new hardware" detection process. Therefore, when you add a second processor, the MP files (HAL and kernels) are automatically installed, and you do not have to manually update the driver in Device Manager.'

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