Re: [uClinux-dev] How to romfs.img

From: Erwin Authried (eauth@softsys.co.at)
Date: Sat Jan 20 2001 - 06:11:12 EST


There are a couple of different choices for romfs. One that Tom hasn't mentioned
is the MTD package that supports many different memory devices, like
RAM, ROM and CFI-compliant flash. The memory range that is used
is either specified in the MTD configuration, or it is determined by
probing, dependent on the drivers that are used. The block memory
driver (blkmem.c) is not needed, MTD has it's own read-only block 
driver (mtdblock_ro.c) that is usable with uClinux. Look at 
  http://uclinux.home.at/, under Architectures -> ARM7 -> Atmel EB01.
This port contains a few hooks that are needed to use the MTD CVS sources
from http://www.linux-mtd.infradead.org.

-Erwin

-----Ursprüngliche Nachricht-----
Von:	Tom Walsh [SMTP:tom@cyberiansoftware.com]
Gesendet am:	Donnerstag, 18. Jänner 2001 21:15
An:	uclinux-dev@uClinux.org
Betreff:	Re: [uClinux-dev] How to romfs.img

> 
> romfs: unable to read superblock
> Kernel: Panic .........
> 
> This must be due to the lack of device inforamtion. I guess somehow I need
> to use "romfs.img" file.  Could you somebody tell me how to use it?
> 
> Is it matter with ROM memory or RAM memory is good enough? I see
> only RAM memory from "mem_init".
> 

The romfs is cat'enated onto the end of the kernel binary image.  When
the kernel is loaded into RAM and the bss section is expanded (you must
move the romfs "up"
 to uncover the bss))., a linked in value for a pointer (mine is ramfs)
points the kernel to the romfs (actually to the end of the kernel
image). See: linux/drivers/block/blkmem.c, this is where most of the
"magic" occurs in mounting a romfs.

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