Re: ACPI global lock macros

[Paul Menage <menage-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>]

Arjan van de Ven wrote:
>>>maybe the odd thing is that it exists at all?
>>>(eg why does ACPI need to have it's own locking primitives...)
>>
>>Because the ACPI spec defines its own locking protocol for 
>>synchronization between the OS and the BIOS.
> 
> 
> ... which can't be written based on linux locks ?

I assume (hope!) there's already a higher-level linux lock serializing 
access to acpi_acquire_global_lock() although I've not delved deeply 
into the code. This is the lock described on p112 of 
http://www.acpi.info/DOWNLOADS/ACPIspec-2-0c.pdf, which has the 
semantics that if the OS wants to take the lock while the BIOS holds it, 
it sets a bit and waits for an interrupt from the BIOS. I don't see that 
it could be naturally implemented using a linux lock.

Paul



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