Eric Lucas on 20 Feb 2013 05:57:22 -0800


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[PLUG] Panic (kernel that is)

I'm trying to create a Mondorescue disk[1] for a computer system that's running a real-time variant of Red Hat Enterprise Linux 5.4 (yeah, old) called "Red Hawk".    The system is an x86_64 mobo with two sata disks in a Linux software RAID mirror.
 
Mondo uses a program called mindi[2] to create it's boot disk and I'm using mindi by itself to create a test boot disk.  Mindi uses the system's own kernel and (apparently) builds a new initrd.img.  It runs mindi-busybox[3] for a lightweight minimal interface.
 
When booting the system from that disk the kernel panics.  It says:
 
"No filesystem could mount root, tried: ext3 ext2 vfat msdos iso9660 udf xfs"
 
The system has the usual /dev/sda and /dev/sdb with all the partitions of type Linux raid autodetect.
At first I thought it was a problem with the kernel detecting the RAID drives but now I'm thinking it's having trouble accessing the ram disk.  That's because on the iso in the isolinux.cfg file there is this:
 
label expert
        kernel /vmlinuz
        append initrd=/initrd.img root=/dev/ram0 rw ramdisk_size=151552 expert devfs=nomount noresume selinux=0 barrier=off udevtimeout=10
 
Ah ha!  root is /dev/ram0
So how do I tell if a kernel has built-in support for ramdisk?  I'm thinking this would be part of any Linux kernel.  I don't see anything in the .config file for it.  The /boot directory on the system contains an initrd.img
 
On a related note: at boot, the console messages flash by and when the kernel panics I'm left with one frozen screen of information.  Is there a way that I can get the boot messages to be sent to the serial port where I could capture it?  The system has no serial port but it does have a usb->serial cable (and my laptop has a serial port!)  It's a SuperMicro mobo and I did not see anything obvious in the BIOS settings like "Enable Serial Console output" :-)  I've never worked with the serial console before so I'm not sure what it's capable of or how to set it up.
 
Thanks,
Eric
 
[1]  http://www.mondorescue.org/
[2]  http://www.mondorescue.org/docs/mondorescue-howto.html#OVERVIEW-MINDI
[3]  http://www.busybox.net
 
--
# Eric Lucas
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