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Date: Wed, 21 Dec 2005 05:21:01 +0100
From: Voluspa <lista1@telia.com>
To: torvalds@osdl.org
Cc: linux-kernel@vger.kernel.org
Subject: Re: Linux 2.6.15-rc6
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I know that C1 isn't much of a power save, but that's what my amd64
notebook provides, and it get used in 2.6.14:

loke@sleipner:~$ cat /proc/acpi/processor/CPU0/power
active state:            C1
max_cstate:              C8
bus master activity:     00000000
states:
   *C1:                  type[C1] promotion[--] demotion[--] latency[000] usage[01399981]

Not so in 2.6.15-rc2 to -rc6 (report http://marc.theaimsgroup.com/?l=linux-kernel&m=113498252000221&w=2 )
Culprit is the following commit that I humbly ask to be removed/rewritten:

root@sleipner:/home/git/linux-2.6# git bisect bad
2203d6ed448ff3b777ee6bb614a53e686b483e5b is first bad commit
diff-tree 2203d6ed448ff3b777ee6bb614a53e686b483e5b (from 2656c076e31a3ce3ab2a987a578e7122dc2af51d)
Author: Linus Torvalds <torvalds@g5.osdl.org>
Date:   Fri Nov 18 07:29:51 2005 -0800

    Fix ACPI processor power block initialization

    Properly clear the memory, and set "pr->flags.power" only if a C2 or
    deeper state is valid (to make the code match both the comment and
    previous behaviour).

    This fixes a boot-time lockup reported by Maneesh Soni when using
    "maxcpus=1".

    Acked-by: Maneesh Soni <maneesh@in.ibm.com>
    Signed-off-by: Linus Torvalds <torvalds@osdl.org>

:040000 040000 52be621b960ae192b36acf778c966d78ff5edbe2 04c183ce141dab8cdff049c1dae379104b637ed4 M      drivers

Mvh
Mats Johannesson
--