From: "Clint Thomas" <[EMAIL PROTECTED]>
To: <[email protected]>
Subject: MTD and U-boot
Date: Wed, 28 Feb 2007 13:41:36 -0500
Hey,
I want to be able to write/read from the same boot flash U-boot resides
on. Right now, u-boot and the vmlinux.img reside on the same 16bit NAND
flash. Is it possible to setup the flash so that from linux, I can erase
and write an updated vmlinux.img when I want to update a kernel build on
the system, without partitioning off a section of it away from U-boot?
Clinton Thomas
Not sure if this is exactly what I think it is, but I asked a similar
question to this a couple weeks ago and didn't get any response. So I will
tell you what I found out (for my case only).
We have a PPC Bug boot image in our flash and we have partitioned off 5
areas in the kernel mtd_physmap, one of which is used to store the
compressed kernel image file and root disk all in one (PPC bugboot image
file)
I wrote some code to extract the entire contents of the "kernel" partition
and save off the binary to a file. Then I figured out how my actual flashed
kernel image matched up with the offsets into that partition, and from that
was able to determine how to change the kernel image in flash to my new
image from a currently booted and running kernel. I was using the MTD flash
device drivers and basically did something in userspace code like:
fd = open("/dev/mtd/1")
read from fd X bytes and store in file where X is size of kernel partition
use hex editor to compare real file image to contents of flash dumped file
and determine offset into flash for start of actual bugboot image. (this
works for us, because we only have a kernel image in that flash space and
nothing else)
so in the update/reprogram software it goes something like:
eraseall /dev/mtd/1
fd = open("my new image file")
fd2 = open("/dev/mtd/1")
seek up to correct offset on fd2 (or just write zeros until the proper
offset is reached)
loop over fd:
read data from fd
write bytes into fd2
that's it.. then reboot and bingo... new kernel image is running...
_________________________________________________________________
Don’t miss your chance to WIN 10 hours of private jet travel from Microsoft®
Office Live http://clk.atdmt.com/MRT/go/mcrssaub0540002499mrt/direct/01/
_______________________________________________
Linuxppc-embedded mailing list
[email protected]
https://ozlabs.org/mailman/listinfo/linuxppc-embedded
