[Novalug] kernel pci probe question

[Mark Smith]

a device label does not exist yet during installation time.  our
normally running systems use labels happily.  the problem is during
installation.  we decide where root is going to be based on device
names.  for instance, if the device name changes from sda to sdb we
could be installing root on a 5TB system (stupid) and a data partition
onto a 100G partition.

there are other ways around this, but the question doesn't the kernel
do its own pci bus probe?  what conditions need to occur to change these
orderings without actually moving disk or cards around?  can this possibly
be caused by any BIOS setting?

On Thu, Apr 03, 2008 at 05:25:29PM -0400, Mike Shade wrote:
> Mark,
> 
> Investigate what's necessary to boot via volume label rather than device
> ID.  I have a wonky motherboard that between various revisions of the kernel
> likes to rearrange the disks -- from those on the auxiliary SATA chipset to
> those on the main motherboard and vice versa.  Here's an excerpt of my
> /etc/fstab to show you what I mean.
> 
> LABEL=/                 /                       ext3    defaults        1 1
> LABEL=/boot             /boot                   ext3    defaults        1 2
> 
> On Thu, Apr 3, 2008 at 5:23 PM, Mark Smith <mark at winksmith.com> wrote:
> 
> > i'm assuming the boot order is cdrom first.  i then boot off of a
> > cdrom, it runs isolinux and in moments there is a running linux
> > kernel.  what happens after that is the interesting bits.  /dev/sda,
> > /dev/sdb, /dev/sdc, ... are fixed via the kernel's own pci probe.
> >
> > On Thu, Apr 03, 2008 at 05:17:05PM -0400, greg pryzby wrote:
> > > -----BEGIN PGP SIGNED MESSAGE-----
> > > Hash: SHA1
> > >
> > > I don't recall the specifics, but I do recall that you can use by-name
> > > and that uses a long identifier (or maybe it was by-identifier) that
> > > isn't dependent on boot order.
> > >
> > > maybe I will research it later and see if I can find the answer....
> > >
> > > Mark Smith wrote:
> > > > my company makes an appliance-like device which includes linux as
> > > > its core.  our software is setup to use specific devices for specific
> > > > file systems.  in particular we have one appliance with a RAID setup
> > > > which is on sda.  the problem is that every now and then it shows
> > > > up on a different device special file.
> > > >
> > > > my questions...
> > > >
> > > > is there any possible setting in the BIOS that can change the
> > > > ordering of devices?  it was my understanding that the kernel does
> > > > its own hardware probe and does not rely on anything the BIOS
> > > > provides in that regard.
> > > >
> > > > what else could change the ordering of devices sans actually moving
> > > > the card position in the chassis or the connectors on the disk arrays?
> > > >
> > > >
> > >
> > > - --
> > > greg pryzby                              greg at pryzby dot org
> > > fingerprint: 8A1A DB90 869F 5DD1 D6E9 EEB6 C156 6B04 849F A86F
> > > -----BEGIN PGP SIGNATURE-----
> > > Version: GnuPG v1.4.6 (GNU/Linux)
> > > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org
> > >
> > > iD8DBQFH9UlQwVZrBISfqG8RAsjzAJ9GXxQzhs09cHMr+db7eCe4nDij0ACffzjt
> > > BzdPxaMKU21YTTWTllFv2bo=
> > > =IYul
> > > -----END PGP SIGNATURE-----
> >
> > --
> > Mark Smith
> > mark at winksmith.com
> > mark at tux.org
> > _______________________________________________
> > Novalug mailing list
> > Novalug at calypso.tux.org
> > http://calypso.tux.org/cgi-bin/mailman/listinfo/novalug
> >

-- 
Mark Smith
mark at winksmith.com
mark at tux.org