[183] in linux-scsi channel archive
Re: SCSI disk SPIN-UP on pwr-up ?
daemon@ATHENA.MIT.EDU (Drew Eckhardt)
Fri May 19 17:38:41 1995
To: Andreas.Koppenhoefer@studbox.uni-stuttgart.de (Andreas Koppenhoefer)
cc: linux-scsi@vger.rutgers.edu, pe1chl@wab-tis.rabobank.nl
In-reply-to: Your message of "Fri, 19 May 1995 21:28:20 +0200."
<199505191928.VAA00280@koppenas.informatik.uni-stuttgart.de>
Date: Fri, 19 May 1995 14:59:12 MDT
From: Drew Eckhardt <drew@boulder.openware.com>
In message <199505191928.VAA00280@koppenas.informatik.uni-stuttgart.de>, koppen
as@koppenas.informatik.uni-stuttgart.de writes:
>-----BEGIN PGP SIGNED MESSAGE-----
>
>> In <blevinD8s9xG.8Aq@netcom.com> blevin@netcom.com (Bryan Levin) writes:
>>
>> >On many unix workstations, the scsi disks only spin up with a scsi command.
>> >As such, most hard drives (I've encountered) don't spin up until told to do
>> >so.
>>
>> [...]
>> Who added this spin-up code? Did it work?
>
>I don't know origin of spin-up code, but it works for my FUJITSU
>M2694ES-512 which has a dip-switch for spin-up at power up.
>
>However I've encountered another problem with spin-up code. Since I'm
>booting from ide disk, I stripped down kernel to include rudimentary
>drivers only. While loading aha1542 module with insmod my scsi disk
>keeps sleeping - no spin-up!
>
>What's the difference between loading scsi driver as module versus
>using as compiled in kernel driver?
In sd_init_onedisk() this if clause
if (current == task[0]){
...
will get executed at startup, but not when the disk driver is installed
as a module, since current will point to some user process and not the
swapper process.
IMHO, it would probably be a good idea to allways execute the code inside
the if clause, since this will handle drives that were powered up after
the system booted - ie, on a laptop with a pcmcia SCSI.
Any objections?
