I'm trying to get working OpenWRT on my brand new Bullet5M (150Mbps)... With ubnt firmware -> 8 Mbyte/s with a wget HTTP download on a 6km line of sight long shoot... That's a pretty cool device 
At the moment, kernel is loaded in RAM via TFTP with the "tftpboot" command but I can't mount rootfs. Maybe because of U-Boot does not use RedBoot; maybe I have to change something in the kernel config.
Here are my manipulations :
Thanks to my RS323 header, I get device console (such as Nanostations, Foneras or Meraki) but parameters are 115200 8N1.
U-Boot 1.1.4 (Apr 22 2009 - 17:30:22)
Board: Ubiquiti Networks ar7240 based board
DRAM: 32 MB
Flash: 8 MB
Net: eth0, eth1
Hit any key to stop autoboot: 0
ar7240>
ar7240>
ar7240>Ok, it's a ar7240 based device. I built OpenWRT firm for ar7240 atheros arch :
# Getting last SVN snapshot
svn co svn://svn.openwrt.org/openwrt/trunk/ kamikaze
cd kamikaze
# Configure OpenWRT
make menuconfig
-> Target System (Atheros AR71xx/AR7240/AR913x [2.6])
-> Target Profile (Ubiquiti Products)
-> Kernel modules-> Wireless drivers -> kmod-madwifi
# Compile
make
# Copy kernel in my tftp root
bin/openwrt-ar71xx-uImage-lzma.bin /tftpboot/1401A8C0.imgNow I can load kernel in RAM, without writing flash (for the moment...)
ar7240>
ar7240> tftpboot
*** Warning: no boot file name; using '1401A8C0.img'
Using eth0 device
TFTP from server 192.168.1.254; our IP address is 192.168.1.20
Filename '1401A8C0.img'.
Load address: 0x81000000
Loading: #################################################################
#################################################################
##########################
done
Bytes transferred = 794890 (c210a hex)And finally boot
ar7240> bootm
## Booting image at 81000000 ...
Image Name: MIPS OpenWrt Linux-2.6.30.5
Created: 2009-08-28 20:20:17 UTC
Image Type: MIPS Linux Kernel Image (lzma compressed)
Data Size: 794826 Bytes = 776.2 kB
Load Address: 80060000
Entry Point: 80060000
Verifying Checksum ... OK
Uncompressing Kernel Image ... OK
Starting kernel ...
Linux version 2.6.30.5 (adrien@solstice) (gcc version 4.1.2) #7 Fri Aug 28 22:20:09 CEST 2009
console [early0] enabled
CPU revision is: 00019374 (MIPS 24Kc)
Atheros AR7240 rev 2, CPU:400.000 MHz, AHB:200.000 MHz, DDR:400.000 MHz
Determined physical RAM map:
memory: 02000000 @ 00000000 (usable)
User-defined physical RAM map:
memory: 02000000 @ 00000000 (usable)
Initrd not found or empty - disabling initrd
Zone PFN ranges:
Normal 0x00000000 -> 0x00002000
Movable zone start PFN for each node
early_node_map[1] active PFN ranges
0: 0x00000000 -> 0x00002000
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 8128
Kernel command line: rootfstype=squashfs,yaffs,jffs2 noinitrd console=ttyS0,115200
Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
Primary data cache 32kB, 4-way, VIPT, cache aliases, linesize 32 bytes
Writing ErrCtl register=00000000
Readback ErrCtl register=00000000
NR_IRQS:56
PID hash table entries: 128 (order: 7, 512 bytes)
Dentry cache hash table entries: 4096 (order: 2, 16384 bytes)
Inode-cache hash table entries: 2048 (order: 1, 8192 bytes)
Memory: 29624k/32768k available (1887k kernel code, 3144k reserved, 359k data, 136k init, 0k highmem)
SLUB: Genslabs=7, HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
Calibrating delay loop... 266.24 BogoMIPS (lpj=1331200)
Mount-cache hash table entries: 512
net_namespace: 528 bytes
NET: Registered protocol family 16
MIPS: machine is Generic AR71xx board
bio: create slab <bio-0> at 0
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 1024 (order: 1, 8192 bytes)
TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
TCP: Hash tables configured (established 1024 bind 1024)
TCP reno registered
NET: Registered protocol family 1
squashfs: version 4.0 (2009/01/31) Phillip Lougher
Registering mini_fo version $Id$
JFFS2 version 2.2. (NAND) (SUMMARY) © 2001-2006 Red Hat, Inc.
yaffs Aug 27 2009 00:07:38 Installing.
msgmni has been set to 57
io scheduler noop registered
io scheduler deadline registered (default)
Serial: 8250/16550 driver, 1 ports, IRQ sharing disabled
serial8250.0: ttyS0 at MMIO 0x18020000 (irq = 11) is a 16550A
console handover: boot [early0] -> real [ttyS0]
Atheros AR71xx SPI Controller driver version 0.2.4
Atheros AR71xx hardware watchdog driver version 0.1.0
TCP westwood registered
NET: Registered protocol family 17
802.1Q VLAN Support v1.8 Ben Greear <greearb@candelatech.com>
All bugs added by David S. Miller <davem@redhat.com>
VFS: Cannot open root device "" or unknown-block()
Please append a correct "root=" boot option; here are the available partitions:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block()