Re: Linix-3.6.3 sda, sdb drives in reverse order (with a USB 2.0drives and a monolithic kernel configuration)

From: Chris Friesen
Date: Fri Oct 26 2012 - 16:22:28 EST


On 10/26/2012 01:43 PM, Wallak wrote:
Chris Friesen wrote:
On 10/25/2012 04:49 PM, Wallak wrote:
I've a very annoying behavior with the linux-3.6.x kernels release, and
a monolithic configuration. The USB 2.0 drives are mapped first with
/dev/sda, /dev/sdb... devices, and than the SATA AHCI drives come after.
This is out of order with the BIOS configuration and breaks a program
like lilo. This is also annoying when we use a static partition mapping.

Linux-3.5 works fine. Where this bug come from ? Is this a patch to get
the old, and classical behavior ?

As you have discovered it's fragile to rely on /dev/sd* names since a
BIOS update, kernel update, or motherboard replacement could
conceivably cause them to change.

Better to use something like partition labels that you control and
that don't change.

Chris

You are right, when we have a configuration with a lot of drvies and
adapters SATA, old SCSI,.. etc. the order may change. But having the
main SATA hard drive defined, as the BIOS boot device, behind external
and removable USB drives is in my opinion a bug.And may lead to security
issues (drives with the same label, etc...).

Using =LABEL, or =UUID with a bootloader like grub or lilo, save the the
boot device mapped drive partition number , and so booting on an older
kernel like linux 3.5 will fail. If we remove the external USB drive,
the boot process will fail too...

So such a bug have to be fix.

If you specify "root=LABEL=<label>" as part of the kernel boot args in grub does it not check the label at boot time?

Chris
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/