[vox-tech] ramdisk error booting Gentoo Linux

[Matt Holland]

> In short, I would examine enabling RAMDisk support and Loopback support in
> your kernel. (Check block devices in make menuconfig for RAMDISK and
> Loopback if you need them - you can also set your default RAMDIsk size
> too for new RAMDisks that are enabled.)


I made sure that RAMDISK was enabled, and I left the RAMDISK size set to 
the default value (I believe it was 4096, but I dunno if that's in bytes 
or Kb).  I also recall enabling loopback support, but couldn't find the 
line in .config this morning when I gave it another (cursory) look.

 
> Second, look at what dd is being called. If they size of data being
> written by dd is greater than the default RAMDisk, then you may want to
> change the default size when setting that option or ???


Is this going to be somewhere in the init scripts?  I must admit that I 
don't know much about what goes on between the beginning of the boot 
sequence and the appearance of the login prompt (perhaps I should read 
the "From power up to bash prompt HOWTO").  What I do know is that the 
Gentoo folks say "Gentoo linux bootscripts require either tmpfs or 
ramdisk support in the kernel," which is why I made sure I included 
ramdisk support, since tmpfs is not available in 2.2.


> If you need ramdisk support before other filesystems are mounted make it
> part of the kernel not a module.


I answered "Y", not "M", so it should be part of the kernel.


> Verify the mointpoint "/mnt/.init.d..." actually exists if you presently
> have ramdisk support enabled.


Ah man, I so hoped that was the problem, but alas, the mountpoint does 
exist, so it's not so simple.

 
> Also, what is dd being used to do with your RAMdisk?
> 
> If you have a ramdisk-device enabled, you cane:
> mkfs -t ext2 /dev/ram0
> mount -t ext2 /dev/ram0 /mnt/point/here


Can I try this at the point where I get the message "Give root password 
for maintenance..."?  I guess my ignorance of exactly what state the 
system is in at this point leaves me a bit confused.  Is it correct to 
say that by the time I get my error, the kernel has made nice with most 
of the hardware and is just getting ready to start system services, so 
basic things like your suggested commands should work?  Please pardon my 
ignorance... you can say RTFM if you want!


> Why not try each operation manually from their kernel?
> 
> See if you can create a RAMDisk for use as a mountable filesystem. See if
> you have the mount point they are looking for.See if it is requiring
> writing to the ramdisk monted system.


I'll try some stuff.  Thanks a lot for the suggestions


>>This is on a new Gentoo Linux system that I built... er, almost built. 
>>I suspect that I may have screwed something up in the kernel build 
>>(something involving ramdisk support?), or maybe just in configuring 
>>Grub.  I'm using a custom compiled version 2.2.20 kernel, because I have 
>>an old ATAPI cd-rom that can't seem to mount media under 2.4 kernels. 
>>That's a little nonstandard for Gentoo, so it's possible that I followed 
>>all of the instructions correctly, but that the instructions were 
>>wrong... pardon the rambling.
>>
> 
> That seems odd. Care to share your /proc/filesystems ?
> 
> Does it include iso9660? Did you include support for this in your 2.4
> kernel? How aboiut MS Joliet support?
> (These options in kernel compilation can be found in the filesystems
> section.)


I know, I thought it was odd as well, but I'm pretty sure that this 
particular cd-rom has never worked with 2.4 kernels.  I originally 
noticed the problem when the same drive was in my main box running 
RedHat 7.0 or 7.1.  Strangely, I could use the cd-rom to install the 
system, but after that, I couldn't mount a filesystem (and yes, all of 
the filesystem support was there, this happened with stock kernels; 
besides the same systems were able to mount iso images as loopback 
devices).  I actually wrote to vox-tech with this problem last fall, and 
Pete tried valiantly to solve it, but we couldn't get it.  The ultimate 
solution was to buy myself a DVD drive, which was a welcome addition to 
the system ;)  However, now I'm trying to use the old drive in a "new" 
system (read: scavenged parts), and installs of Mandrake 7.1 and RedHat 
7.x have worked fine, with the exception of the cd-rom.  I was hoping 
Gentoo would be different (for the record, in case Pete's reading this, 
Debian Potato was also fine... but I really like the idea of Gentoo). 
My guess is that something happened to the ATAPI cd-rom driver that 
"left behind" a certain class of older drives; unfortunately, it's 
beyond my abilities to find and fix such a bug if it really exists.


>>In any case, I'm wondering if anyone has seen a problem like this after 
>>compiling a new kernel; if so, any idea what's causing it?  A newsgroup 
>>search didn't turn up anything helpful (or even relevant), so I thought 
>>I'd let you guys take a crack at it before turning to gentoo-user.
>>
> 
> If the problems exist after a new kernel, but not in earlier ones, and you
> are using the stable siries (lik 2.2, 2.4 etc) then odds are in favor of
> an unset option in your kernel config.


Well, unfortunately, there is no "earlier" kernel, aside from the one on 
the boot/rescue disk.  This makes it a bit of a pain to fix, since in 
order to compile a new kernel, I have to boot with the rescue disk, 
mount my filesystems by hand, chroot, and go through the configuration 
process again.  I think maybe I'll try a 2.4 kernel next, b/c that 
should be more straightforward to get running since Gentoo was designed 
with 2.4 kernels in mind.


In any case, thanks for the ideas.  I guess I'll have to start getting my hands dirty!


Matt