Hi,

I have a custom Linux installation that resides in a NAND flash chip that acts as the root drive. It boots up fine when the drive is read/write. However when I jumper the drive to read-only, which is its final state, it fails to load.

I'm using kernel 2.6.22.19 and LILO boot loader. In lilo.conf I have already included "read-only".

The file system seems to already be in read only mode since I'm unable to create files once I'm booted up w/o the jumper. I don't understand why then does it not boot when I jumper it to read only? When I do this, once the kernel decompresses I get nothing, no debug messages even. It just hangs there.

Thanks.

Hello,

I will try to see if my logic may make sense here but when you say that you have your root drive as read only I could see how you may be getting the problems that your are getting. What I mean by that is if I am looking at this correct your root drive will consist of /, /var, /etc, /home, /tmp, /opt, /root and maybe others don't know what all you may have created in the form of filesystems on it. This will have to be a writeable drive since at the time of boot your hardware is walked and things get stored in /dev with new timestamps and if you can't write to the drive I can see several things failing. Even things in /var and /tmp could be created for temp files and jobs so I really don't see how the drive if it is a true root drive in what I am thinking of root as in all of the base default dirs which the system must have to be able to run. Hope that helps I just don't see how linux or any unix will work in a read only mode for the root of the OS when it creates and writes new data to files but at the same time I really don't know what all you have done in your custom Linux install don't know if was written to not do what a normal linux install does.

Thanks. My kernel booting up doesn't write to the drive. My "init" is simply a busybox shell. I've actually found the problem to be pertaining to LILO, and I've fixed it. Thanks again!

Just for the sake of completeness:
Could please post what the exact problem was with the LILO settings and how you'd fixed it?
Thanks!

linux

Sorry, forgot to include that.

Well, you know LILO's "BIOS data check successful" message? Apparently after that, it writes some status messages to the drive. Since my drive is write-protected, it hangs there. After I include "suppress-boot-time-BIOS-data" in lilo.conf, it bypasses the check and hence works.

I'm curious --

How are you solving the /dev /var /tmp writability issue raised by shadow5277?
What is actually on the NAND flash chip & what is linked elsewhere?
Linked to where?
With what mechanism, i.e. are you using Aufs or UnionFS, or possibly something else?