USB Boot Problem
On Wed, Feb 10, 2010 at 10:57 AM, Relson, David
<david.relson@orion-sys.com> wrote:
>
> G'day,
>
> I've got a USB boot problem.
>
> My target hardware is a PC/104 card with a Vortex86sx processor and a
> 128MB DOM (disk-on-module) for mass storage.
>
> Currently the test version of the card has a 1GB DOM which is
> partitioned as follows:
>
> * * * Device Boot * * *Start * * * * End * * *Blocks *Id System
> * */dev/hda1 * * * * * * * 1 * * * * 141 * * *142096+ *6 FAT16
> * */dev/hda2 * * * * * * 142 * * * * 991 * * *856800 *83 Linux
>
> The BIOS boots to the FAT16 partition where ldlinux.sys takes over and
> starts linux and all is fine.
>
> When I insert my USB flash drive, it is recognized as:
>
> * *usb 1-1.2: new high speed USB device using ehci_hcd and address 3
> * *usb 1-1.2: configuration #1 chosen from 1 choice
> * *scsi0 : SCSI emulation for USB Mass Storage devices
> * *usb-storage: device found at 3
> * *usb-storage: waiting for device to settle before scanning
>
> * *scsi 0:0:0:0: Direct-Access * SanDisk *Cruzer Micro *0.1 *PQ: 0
> ANSI: 2
> * *sd 0:0:0:0: [sda] 2001888 512-byte hardware sectors: (1.02 GB/977
> MiB)
> * *sd 0:0:0:0: [sda] Write Protect is off
> * *sd 0:0:0:0: [sda] Mode Sense: 03 00 00 00
> * *sd 0:0:0:0: [sda] Assuming drive cache: write through
> * *sd 0:0:0:0: [sda] 2001888 512-byte hardware sectors: (1.02 GB/977
> MiB)
> * *sd 0:0:0:0: [sda] Write Protect is off
> * *sd 0:0:0:0: [sda] Mode Sense: 03 00 00 00
> * *sd 0:0:0:0: [sda] Assuming drive cache: write through
> * * sda: sda1
> * *sd 0:0:0:0: [sda] Attached SCSI removable disk
> * *usb-storage: device scan complete
>
> I need to create a rescue/install USB flash drive.
>
> At present my test flash drive has ldlinux.sys and the same kernel used
> by the device. *Booting with "linux root=/dev/hda2" works fine. *However
> for rescue purposes I need "linux root=/dev/sda" (or equivalent).
>
> When I boot with "linux root=/dev/sda1", I get the following
>
> * *VFS: Cannot open root device "sda1" or unknown-block(0,0)
> * *Please append a correct "root=" boot option; here are the available
> partitions:
> * *0300 * * *1000944 hda driver: ide-gd
> * * *0301 * * *142096 hda1
> * * *0302 * * *856800 hda2
> * *Kernel panic - not syncing: VFS: Unable to mount root fs on
> unknown-block(0,0)
>
> Evidently /dev/sda1 hasn't yet mounted. *The boot process runs into the
> same problem when I use /dev/sda or /dev/sda2 for "root=".
>
> In the past I've seen similar kernel panics when the kernel lacks the
> proper disk driver. *Since the system boots fine from the DOM, I believe
> my kernel has all the device drivers built in (except scsi_wait_scan.ko
> which is a module).
>
> How do I fix the boot problem? *Anybody familiar with this problem and
> have a recommendation or, even better, a solution?
It's likely that the kernel hasn't fully recognized your USB device
yet (notice the "usb-storage: waiting for device to settle before
scanning" dmesg line?)
Try appending the "rootwait" kernel parameter (kernel waits forever
for the root device to show up), or the "rootdelay=" parameter
(argument is number of seconds to wait). Further information about
these and other related kernel params are in the kernel source tree
under Documentation/kernel-parameters.txt
HTH-
James
>
> Regards,
>
> David
>
>
>
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