[gentoo-embedded] USB progress [ was: USB Boot Problem ]

[David Relson]

On Wed, 10 Feb 2010 20:43:44 +0100 (CET)
joerg.faschingbauer@×××.at wrote:

> >>>>> "David" == Relson, David <david.relson@×××××××××.com> writes:
>
> David> When I boot with "linux root=/dev/sda1", I get the following
>
> David>     VFS: Cannot open root device "sda1" or unknown-block(0,0)
> David>     Please append a correct "root=" boot option; here are the
> David> available partitions:
> David>     0300      1000944 hda driver: ide-gd
> David>       0301      142096 hda1
> David>       0302      856800 hda2
> David>     Kernel panic - not syncing: VFS: Unable to mount root fs on
> David> unknown-block(0,0)
>
> David> Evidently /dev/sda1 hasn't yet mounted.  The boot process runs
> David> into the same problem when I use /dev/sda or /dev/sda2 for
> David> "root=".
>
> David> In the past I've seen similar kernel panics when the kernel
> David> lacks the proper disk driver.  Since the system boots fine
> David> from the DOM, I believe my kernel has all the device drivers
> David> built in (except scsi_wait_scan.ko which is a module).
>
> David> How do I fix the boot problem?  Anybody familiar with this
> David> problem and have a recommendation or, even better, a solution?
>
> You might want to pass "rootdelay=5" (seconds), or "rootwait" for
> newer kernels (don't know when the latter was introduced).
>
> Joerg

Thanks to Manuel, James, and Joerg.  All 3 of you suggested
rootdelay.  It helps but isn't a complete solution.

My syslinux.cfg now contains:

    LABEL linux
    KERNEL linux
    APPEND rootdelay=10 root=/dev/sda1

and is working better than before.

After SCSI messages:

    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

The boot process fails with:

    VFS: Mounted root (vfat filesystem) readonly on device 8:1
    Freeing unused kernel memory: 176k freed
    Warning: unable to open an initial console
    Kernel panic - not syncing: No init found.  Try passing init=
    option to kernel

Clearly the wait is helping since 'vfat' and '8:1' are correct.  The
"init=" suggestion is puzzling.  The default boot (from the built-in
DOM) uses the following syslinux.cfg:

    DEFAULT linux

    LABEL linux
    KERNEL linux
    APPEND root=/dev/hda2

there's no "init=" in it.  Also, /etc/init.d just contains a single
script (named rcS) which does all the initialization.  There are no run
levels. FWIW, I'm using a 2.6.29.6 kernel.