Subject: Re: DaemonNews article about boot speedups
To: Hubert Feyrer <hubert.feyrer@informatik.fh-regensburg.de>
From: Jason R Thorpe <thorpej@zembu.com>
List: tech-kern
Date: 09/04/2000 19:59:05
On Tue, Sep 05, 2000 at 04:52:12AM +0200, Hubert Feyrer wrote:
> I've just read the DaemonNews article about speeding up the NetBSD boot
> process by saving SCSI device probes. I wonder if hardcoding devices in
> the kernel would be of the same effect:
>
> ahc0 at pci? dev 9 function ? #HF# Adaptec AHA2940U, aic78x0 SCSI
> scsibus0 at ahc0 #HF#
> sd0 at scsibus0 target 1 lun 0 #HF# SCSI disk: 2GB DORS (NT)
> sd1 at scsibus0 target 2 lun 0 #HF# SCSI disk: 4GB DCAS (ccd0 part 1)
> sd2 at scsibus0 target 4 lun 0 #HF# SCSI disk: 4GB DCAS (ccd0 part 2)
>
> Without having any wildcard devices (scsibus*, sd?, ahc?) in the kernel.
> Will this have the same speedup effect, or are the devices in the kernel
> config file still prone to expensive probes?
>
> (I've written a perl script to generate such a optimized kernel config
> file from a template and dmesg output long time ago, see
> www.feyrer.de/Misc/adjustkernel)
For direct-config busses, all devices are probed regardless of the contents
of the config file. The config file is used to match devices to driver
instances.
--
-- Jason R. Thorpe <thorpej@zembu.com>