Unable to mount /dev/root

Igor V. Ruzanov igorr at canmos.ru
Sat May 3 16:45:47 CEST 2008

On Thu, 1 May 2008, Adam Lackorzynski wrote:

> Hi,
> On Wed Apr 30, 2008 at 20:43:17 +0400, Igor V. Ruzanov wrote:
>>>> # CONFIG_HOTPLUG is not set
>>> You need CONFIG_HOTPLUG for udev to work correctly, without this option
>>> you may not get the device-nodes even if you compiled the right drivers
>>> in your kernel.
>> Thanks for your hint! I set CONFIG_HOTPLUG to 'y'. Also i added some
>> derivative options:
>> # CONFIG_HOTPLUG_PCI_CPCI_ZT5550 is not set
>> With them some error messages were disapperred from boot log but the
>> system persists to be dropped into panic after rest of messages:
>> mount: could not find filesystem /dev/root
>> [...]
>> switchroot: mount failed: No such file or directory
>> Kernel panic - not syncing: No such file or directory
>> For little debug i unpacked my initrd image and modified 'init' script
>> with several changes:
>> mount -o defaults --ro -t ext3 sda1 /sysroot
>> showlabels
>> sleep 5
>> where mount command was given in obvious way with telling of root device
>> (in my case its a /dev/sda1 which also i point it in l4linux26.cfg) and
>> showtables to show what are devices/partitions and their labels are
>> exactly seen by nash. Noone of sd{a|b} devices was listed during of
>> next boot log.
>> my l4linux26.cfg looks like:
>> sleep 1
>> task "vmlinuz-2.6.24-l4" "earlyprintk=yes mem=512M ro root=/dev/sda1 l4env_rd=initrd-2.6.24-l4.img"
>> all_sects_writable
>> allow_vga
>> i even tried to change root=/dev/sda1 with root=LABEL=/ as labeled my
>> /dev/sda1 partition.
>> I suppose that my mistake could be in absence some kernel options that
>> might be very specific for my hardware configuration:
>> CPU: Pentium Dual Core, 2GHz
>> RAM: 2048 Mb
>> Chipset: Intel G33 Express
>> HDD: SATA, 250Gb
>> or there is hypothetical way to 'dig' the problem from some another side ;)
> Your hardware does not look special in any way.
> Do you see output like
> sd 0:0:0:0: [sda] 156301488 512-byte hardware sectors (80026 MB)
> sd 0:0:0:0: [sda] Write Protect is off
> sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
> sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
> sda: sda1 sda2
> when the modules load? Especially the last line is important as it
> states that the partitions were found.

No, i don't see such logs. Exactly output of rest of the boot looks like:

[...some messages about loading of usb modules, hotplug configuring...]
Loading scsi_mod.ko module
SCSI subsystem initialized
Loading sd_mod.ko module
Driver 'sd' needs updating - please use bus_type methods
Loading libata.ko module
Loading ahci.ko module
Waiting for driver initialization
Creating root device
Mounting root filesystem
mount: could not find filesystem '/dev/root'
[...and still several messages about impossibility of mounting /sys and 
/proc filesystems before terminating of init and panic state...]

I'm trying to research problem towards of PCI probing through mmconfig.. 
In my kernel config is CONFIG_PCI_GOMMCONFIG=y used. GODIRECT resulted 
__unknown_pf(). It might be due to some mmconfig failures during l4linux 
boot and incorrect work of ahci driver as result.

Unfortunately i cannot provide you full log of l4linux boot stages because 
i haven't any methods (physical COM-port with attached machine as a 
console with X11 and some console application with text buffering). Does 
theoretically (at least) mmconfig can make problems within l4env?

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