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From: Paul Menage <menage@google.com>
To: Arjan van de Ven <arjanv@redhat.com>
Cc: agrover@groveronline.com, linux-kernel@vger.kernel.org,
	acpi-devel@lists.sourceforge.net
Subject: Re: ACPI global lock macros
Date: Tue, 09 Dec 2003 01:50:16 -0800	[thread overview]
Message-ID: <3FD59AD8.1060507@google.com> (raw)
In-Reply-To: <20031209094356.GA19702@devserv.devel.redhat.com>

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


  reply	other threads:[~2003-12-09  9:51 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-12-09  9:22 ACPI global lock macros Paul Menage
2003-12-09  9:36 ` Arjan van de Ven
2003-12-09  9:42   ` Paul Menage
2003-12-09  9:43     ` Arjan van de Ven
2003-12-09  9:50       ` Paul Menage [this message]
2003-12-10  7:45 ` [ACPI] " Andi Kleen

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