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Date: Wed, 31 Jul 2002 16:10:48 -0400 (EDT)
From: Bill Davidsen <davidsen@tmr.com>
To: Ray Lee <ray-lk@madrabbit.org>
cc: Linux Kernel <linux-kernel@vger.kernel.org>, cort@fsmlabs.com,
       alan@lxorguk.ukuu.org.uk
Subject: Re: [PATCH] Guarantee APM power status change notifications
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On 31 Jul 2002, Ray Lee wrote:

> There are three cases. First, the BIOS doesn't send any notifications;
> this is fixed. Second, the BIOS sends notifications. In this case, the
> code notes that, and disables the workaround. Third, the BIOS sends
> notifications, but somehow we managed to notice the power change before
> the BIOS could tell us. This seems highly unlikely, but what the heck,
> it could theoretically happen. In that case, we disable the workaround,
> and drop the notification that the BIOS generated, as we already sent it
> onward up the call chain.

Actually there is one more case, where the BIOS unreliably tells you
something has changed. I have an old Toshiba which I bought with Windows
installed, and it always noticed pulling the plug and going line=>battery,
but only sometimes noticed battery=>line. Of course this might be an o/s
bug. Can't test that any more, the battery failed and the transition is
now line=>dead.

Anyway, if you are paranoid you could just ignore the "I knew that" cases
and leave the workaround in place, unless that would generate other
issues.

-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

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