Re: [gentoo-mips] Question - Kumba LiveCD RC6

[Kumba]

Mike Martin wrote:
> I recently downloaded and attempted to boot an Octane with this disk. It
> died mounting the root partition:
>
> mount: Mounting /newroot/dev/loop0 on /newroot/mnt/livecd failed:
> Invalid argument
>
> Not sure what happened. I assume I burnt the disk correctly else it
> wouldn't have made it that far. Any suggestions?
>
> MikeM


It's really hard to say.  I tested it on all of my systems before uploading, and 
  with the Octane, this means an external drive (funny enough, an O2 CD drive 
jammed into a Sun 411 case).  And that booted fine on both my Octane and Indy.

"Invalid Argument" from mount could mean a wide array of things (yay for Unix's 
legacy of non-descriptive, ambiguous errors).  The process that occurs on an SGI 
bootcd for us is a rather complex one:

1. arcload boots from the DVh partition of the CD
	(yes, these CDs have partitions)
2. arcload finds and boots a kernel
3. kernel loads, and executes /init in an embedded initramfs file linked
	into the kernel
4. /init does some prep work, and launches `getdvhoff` to scan the CD
	for the offset of the next partition (where / lives), and passes a
	number representing this offset back to `losetup`.
5. losetup uses this number to "point" /dev/loop0 at this offset, which
	effectively makes /dev/loop0 a block device with data on it.
6. mount tries to mount /dev/loop0 and pivot_root into the real Gentoo
	filesystem.


Quite likely, step #5 might've failed somewheres along the line.  The offset has 
to be exact to the bit, so maybe something got whacked in the burn and the 
detected offset is invalid.  Hard to say without more information.  Thus, when 
it got to step #6, boom.

I'd try re-burning the disk at a slower speed, use only CD-R's of decent quality 
(TDK, Memorex, Sony, Ricoh/Ritek, etc,.. brands), and use cdrecord (or whatever 
license-unencumbered version is out there.  stupid license wars).  A few people 
reported getting it to work with a windows burn tool, but we have little data on 
that, thus why cdrecord is the suggested tool.

Mostly, you were able to read the kernel into memory, which is ~8MB.  It's 
possible the disc you burned was good enough to get those 8MB off to boot the 
kernel, but when it went looking for the meat, it got denied and pwned.



--Kumba

-- 
Gentoo/MIPS Team Lead

"Such is oft the course of deeds that move the wheels of the world: small hands 
do them because they must, while the eyes of the great are elsewhere."  --Elrond
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