cvs commit: src/sys/dev/pci pci.c

Joao Barros joao.barros at
Sun Sep 18 07:15:18 PDT 2005

On 9/11/05, Warner Losh <imp at> wrote:
> imp         2005-09-11 19:28:31 UTC
>   FreeBSD src repository
>   Modified files:        (Branch: RELENG_6)
>     sys/dev/pci          pci.c
>   Log:
>   Change the default of pci_do_powerstate to 0, per request from re at .
>   The number of raid controllers that violate the WHQL seems to be
>   growing in number and not isolated to old versions as previously
>   thought.  Though the numbers of these seen in the wild is still
>   relatively small, they hang the system when parts of their devices are
>   powered down.  The one area that these parts appear often are in the
>   higher end servers.  As such, be conservative about powering down
>   devices that have no driver attached by default.  Until a better
>   approach is proven in current, this is the prudent choice.
>   Laptop users wishing the benefits of powering down devices with no
>   drivers will now need to set hw.pci.do_powerstate=1 in their
>   /boot/loader.conf file.  Some users will have devices that will
>   prevent this setting (hence the need to make it default 0).
>   Approved by: re@ (scottl)
>   Revision   Changes    Path
>  +2 -2      src/sys/dev/pci/pci.c
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I was reading the Release Notes for 6.0 on
and noticed:

2.2.2 Hardware Support

The acpi(4) driver now turns the ACPI and PCI devices off or to a
lower power state when suspending, and back on again when resuming.
This behavior can be disabled by setting the debug.acpi.do_powerstate
and hw.pci.do_powerstate sysctls to 0.

Given this is the same tunable you changed back to 0 by default, does
that "when resuming" has anything to do with this last commit? If so,
it could still be mentioned the other way around, allowing people
wanting to, to enable the tunable :)

Joao Barros

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