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

[Wallak]

I've found where this issue come from. This behavior was introduced with 
the commit: 0cc15d03bcccdf95e2bd82e094e6064e61b54207.The description is 
available below. Removing this patch fix the drive order.


Best Regards,
Wallak.


commit 0cc15d03bcccdf95e2bd82e094e6064e61b54207
Author: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Date:   Mon Jul 2 17:27:04 2012 -0700

    floppy: Run floppy initialization asynchronous

    floppy_init is quite slow, 3s on my test system to determine
    that there is no floppy. Run it asynchronous to the other
    init calls to improve boot time.

    [jkosina@xxxxxxx: fix modular build]

    Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
    Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>




Wallak wrote:
> Chris Friesen wrote:
> > 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?
>
> Using root=LABEL= or root=UUID= don't work on a plain kernel, this 
> feature may be handled by an initrd trick. Otherwise for all non root 
> partitions UUID= work fine.
> Nevertheless not fixing this bug yields some other issues:  Using lilo 
> to launch a second OS (other= option) fail, the command try to parse 
> partitions available on /dev/sda, and miss the real main HDD. Boot 
> drive must be force with lilo options...
> SATA drives have, most of the time, no reason to be behind USB drives. 
> If we want to get a reliable behavior: /dev/sda must be mapped to the 
> BIOS boot device. Using the same behavior as linux-3.5 will be fine.
>
> Wallak.
>
> > Chris

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