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List:       gentoo-sparc
Subject:    Re: [gentoo-sparc] My first install
From:       Keith M Wesolowski <wesolows () foobazco ! org>
Date:       2003-06-20 19:20:46
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On Fri, Jun 20, 2003 at 08:43:37PM +0200, Patrick Marquetecken wrote:

> the "sun boot disk" is sdb under Gentoo, and the Quantum is sda. If
> i'm correct the actual "boot disk" with the machine uses is stored
> in the Open boot Prom (The sun disk), and shall be sdb ?

Most likely yes.  To clear this up, the PROM has default aliases that
do not match the order in which Linux assigns device IDs.

This is a FAQ, so here goes:

Linux, normally, orders devices by SCSI ID.  The lowest-numbered disk
is sda, the next-lowest is sdb, and so on.  Note that devfs allows you
to specify devices by SCSI ID, so that adding a new device doesn't
cause your existing devices to be renamed, unless of course you use
the compatibility names.  There are additional ways to solve this.

The OpenBoot PROM in most or all sun4c and sun4m systems aliases
"disk" to the device with SCSI ID 3, and "disk0" through "disk3" to
the device with the corresponding SCSI ID, if it happens to be a disk
rather than a tape, CDROM, etc.

In the desktop systems of this era that support two SCA disks (the
Aurora chassis systems), the lower slot is assigned SCSI ID 3, and the
upper slot is assigned SCSI ID 1.

If you like, you can change the PROM alias "disk" to match that of
"disk1" so that the "boot disk" command causes the system to boot from
the same device Linux calls sda.  This feels more consistent and
normal, especially for users with a PC background.  Alternately, you
can simply place the filesystem containing /boot (which could be the
root filesystem or a separate boot filesystem) on device ID 3 (Linux
sdb) and boot from it, using a root filesystem on either sda or sdb,
or in fact any other disk attached to the system.

The desktop Ultras use ID 0 and ID 1, and therefore this is no
difference between Linux's naming and the PROM's.

-- 
Keith M Wesolowski <wesolows@foobazco.org> http://foobazco.org/~wesolows
------(( Project Foobazco Coordinator and Network Administrator ))------
	"May Buddha bless all stubborn people!"
				-- Uliassutai Karakorum Blake

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