I wanted try something other than JFFS2 as the rootfs and decided to go with UBIFS. Thanks to GIT’s brilliance I had no trouble pulling the UBIFS kernel patches from their tree to mine.
It seems that the UBIFS hasn’t had many NOR flash users before me and it needed some fixes. Artem Bityutskiy was extremely helpful in fixing the deficiencies and helping me out. After a few debug rounds I now have UBIFS root on my Gumstix.
I created the UBIFS image with the following commands:
sudo mkfs.ubifs --compr=zlib -r /tmp/rootfs -m 1 -e 130944 -c 120 -o ubifs.img
ubinize -o ubi.img -m 1 -p 128KiB -v ubinize.cfg
With this ubinize.cfg:
Note that I have reserved 2MiB for the kernel partition.
I had to add one extra parameter to the kernel args to specify what MTD partition I wanted to use:
console=ttyS0,115200n8 root=ubi0:rootfs rootfstype=ubifs reboot=cold,hard ubi.mtd=1
Now my Gumstix boots with simplified kernel to busybox shell in roughly 4.2 seconds (counted from the bootm command in U-Boot).
I had to add a new category after all: gumstix. The embedded word has too broad a meaning.
Updating the kernel wasn’t such a big thing after all, even for a kernel n00b like me. I git cloned the vanilla tree from kernel.org and patched the generic (and one bluetooth) Gumstix patches from OE: arch-config.patch, board-init.patch, header.patch, mach-types-fix.patch, modular-init-bluetooth.patch, tsc2003-config.diff, tsc2003.c, and uImage-in-own-partition.patch. Most of them applied fine, I just had to manually apply simple Makefile patches and change pxa_init_irq call to pxa27x_init_irq.
I don’t know if it really works, but at least it booted:
root@gumstix-custom-verdex:~$ uname -a
Linux gumstix-custom-verdex 2.6.25-rc8-00151-gdc41023 #2 Fri Apr 4 23:43:25 EEST 2008 armv5tel unknown
It’s time to create a new category in my projects blog: embedded.
I got interested in microcontrollers some years ago and wrote something simple for 16F88 with assembler. Then I connected it to an old IPAQ using a serial connection. But the IPAQ isn’t a very good development platform so now I decided to buy a gumstix.
It’s 400Mhz verdex mainboard with 64M RAM and 16M flash. And a bluetooth. The mainboard is the smaller board upside down in the picture. The bigger board is a expansion board including 3x rs232, power plug, a USB mini-B connector and a bunch of GPIO lines.
The bootloader is U-Boot and the Linux distribution is based on OpenEmbedded. U-Boot is nice as I’m somewhat familiar with it but the OE I’m going to replace with something else.
I just booted it up to see how it looks inside:
Processor : XScale-PXA270 rev 7 (v5l)
BogoMIPS : 415.33
Features : swp half thumb fastmult edsp iwmmxt
CPU implementer : 0x69
CPU architecture: 5TE
CPU variant : 0x0
CPU part : 0x411
CPU revision : 7
Hardware : The Gumstix Platform
Maybe the first thing would be to configure the kernel to support only those features included in my hardware setup.