Subject: Re: accessing IDE hard drive via pcmcia card (redirected from
To: None <>
From: M. Warner Losh <>
List: tech-kern
Date: 05/23/2004 08:58:43
In message: <>
            Martin Husemann <> writes:
: > FreeBSD powers things up once, and it turns out to be a lot faster to
: > do it this way for real spinning media.  Turns out to be about a wash
: > for non-spinning media or network devices.
: I'm not sure I understand this completely - I suppose you don't let the
: socket powered on unconditionally - even if the drive is not mounted? Is it a
: timeout method, like described above, or do you rely on pccard daemon to do
: the mount imediately? Or are you talking only root mounts only?

FreeBSD powers up the slot when it is inserted.  When no drivers
attach, the slot is powered down.  In the FreeBSD model, the driver
(or some other power management agent) is responsible for turning off
the 'idle' device after a while.  NetBSD is a lot more agressive about
keeping the power off than FreeBSD.  This can be good in some cases,
but bad in others.  For most devices it is a wash, for spinning media,
FreeBSD's method works better.  For a network or modem card that's in
a notebook, but configured down, NetBSD's is better (since it uses
less power).

Anyway, I'm not advocating FreeBSD's method, just providing a