[Bugme-new] [Bug 8935] New: Kernel incorrectly chooses external drive as /dev/sda on approx. 70% of boots

[bugme-daemon at bugzilla.kernel.org]

http://bugzilla.kernel.org/show_bug.cgi?id=8935

           Summary: Kernel incorrectly chooses external drive as /dev/sda on
                    approx. 70% of boots
           Product: IO/Storage
           Version: 2.5
     KernelVersion: 2.6.22
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Serial ATA
        AssignedTo: jgarzik at pobox.com
        ReportedBy: tristan_schmelcher at alumni.uwaterloo.ca


Most recent kernel where this bug did not occur: Unknown
Distribution: Debian
Hardware Environment: Dell XPS M1710 laptop with Intel Core 2 Duo
Software Environment: Debian Etch/Lenny 2.6.22-1-amd64
Problem Description: My laptop has an internal SATA drive and an external eSATA
drive, connected via an ExpressCard-to-eSATA adapter. If the external drive is
plugged in when I boot the machine then the kernel incorrectly chooses it as
/dev/sda approximately 70% of the time, with the internal drive becoming
/dev/sdb. It thus mounts the external drive to "/root" in the initramfs instead
of the internal drive and dies when it can't find "init". If I instead connect
it _after_ booting then it works as normal.

As an uninformed guess, perhaps the non-deterministic choice of /dev/sda stems
from the fact that this is an SMP system, so there is a race to see which drive
is discovered first?

Steps to reproduce:

1) Get a hardware setup similar to the one I've described.

2) Plug in the eSATA drive.

3) Reboot a lot.


The output of lspci for my system is:

$ lspci
00:00.0 Host bridge: Intel Corporation Mobile 945GM/PM/GMS/940GML and 945GT
Express Memory Controller Hub (rev 03)
00:01.0 PCI bridge: Intel Corporation Mobile 945GM/PM/GMS/940GML and 945GT
Express PCI Express Root Port (rev 03)
00:1b.0 Audio device: Intel Corporation 82801G (ICH7 Family) High Definition
Audio Controller (rev 01)
00:1c.0 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 1
(rev 01)
00:1c.1 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 2
(rev 01)
00:1c.2 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 3
(rev 01)
00:1c.3 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 4
(rev 01)
00:1d.0 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI #1 (rev
01)
00:1d.1 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI #2 (rev
01)
00:1d.2 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI #3 (rev
01)
00:1d.3 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI #4 (rev
01)
00:1d.7 USB Controller: Intel Corporation 82801G (ICH7 Family) USB2 EHCI
Controller (rev 01)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev e1)
00:1f.0 ISA bridge: Intel Corporation 82801GBM (ICH7-M) LPC Interface Bridge
(rev 01)
00:1f.2 IDE interface: Intel Corporation 82801GBM/GHM (ICH7 Family) Serial ATA
Storage Controller IDE (rev 01)
00:1f.3 SMBus: Intel Corporation 82801G (ICH7 Family) SMBus Controller (rev 01)
01:00.0 VGA compatible controller: nVidia Corporation Unknown device 0298 (rev
a1)
03:01.0 FireWire (IEEE 1394): Ricoh Co Ltd Unknown device 0832
03:01.1 Generic system peripheral [0805]: Ricoh Co Ltd R5C822
SD/SDIO/MMC/MS/MSPro Host Adapter (rev 19)
03:01.2 System peripheral: Ricoh Co Ltd Unknown device 0843 (rev 01)
03:01.3 System peripheral: Ricoh Co Ltd R5C592 Memory Stick Bus Host Adapter
(rev 0a)
03:01.4 System peripheral: Ricoh Co Ltd xD-Picture Card Controller (rev 05)
09:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5752 Gigabit
Ethernet PCI Express (rev 02)
0c:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG Network
Connection (rev 02)
0d:00.0 SATA controller: JMicron Technologies, Inc. JMicron 20360/20363 AHCI
Controller (rev 02)

I think the chip that does the ExpressCard slot is either the "Intel
Corporation 82801GBM (ICH7-M) LPC Interface Bridge (rev 01)" or the "Ricoh Co
Ltd Unknown device 0843". According to the parts' literature, the former uses a
PCIe-style ExpressCard implementation, while the latter is USB-style. (I get
very little performance gain compared to a USB connection for the same drive,
so it might be the latter.)


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