amd64/171355: FreeBSD 9.1rc1 (and 10-HEAD) not booting on HP Pavilion g6 2147sl

Alexander Motin mav at
Sun Sep 9 20:20:10 UTC 2012

The following reply was made to PR amd64/171355; it has been noted by GNATS.

From: Alexander Motin <mav at>
To: Stefano Marinelli <stefano at>
Cc: attilio at, bug-followup at
Subject: Re: amd64/171355: FreeBSD 9.1rc1 (and 10-HEAD) not booting on HP
 Pavilion g6 2147sl
Date: Sun, 09 Sep 2012 23:11:31 +0300

 On 09.09.2012 23:03, Stefano Marinelli wrote:
 >> Thanks, that explains a lot. AMD started to use their proper vendor ID for HPET, but seems haven't fixed level-triggered interrupts and haven't implemented (removed?) message interrupts. All together it broke workaround in HPET driver that supposed to block HPET by default in such cases. Such patch should restore it:
 > [...]
 > Thank you. I am downloading the sources and will try to patch and recompile the kernel as soon as it will have finished. Then, I will report back.
 >> I can't say about frequency control, never looked inside AMD's PowerNow; but C-states are detected as I can see. You should just enable them by adding to /etc/rc.conf lines:
 >> performance_cx_lowest="C2"
 >> economy_cx_lowest="C2"
 > I tried this, and actually I can see the C2 status is now active. Still, the watt-o-meter I am using shows a 50W power consumption in idle state (wifi is off as unsupported), compared to 23/24 on GNU/Linux (Arch) with wifi on.
 There could be other factors except CPU. For example, GPU, screen 
 backlight, disks, etc. Without having proper video driver for AMD GPUs 
 it is difficult to predict its power consumption. Also you may look on 
 this page: . It was 
 written some time ago and mostly for Intel, but hopefully better then 
 nothing. Unluckily I have no experience with AMD laptops.
 Alexander Motin

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