Preparations
Put the initramfs file in the root of a TFTP Server which listens on 192.168.1.66/24. You can get one from downloads.openwrt.org:
Rename the file to ws-ap3825i-initramfs.bin
For Linux this could something like the following:
# create a temporary directory and enter it:
cd $(mktemp -d)
# dowload the initramfs:
curl https://downloads.openwrt.org/snapshots/targets/mpc85xx/p1020/openwrt-mpc85xx-p1020-extreme-networks_ws-ap3825i-initramfs-kernel.bin -o ws-ap3825i-initramfs.bin
# start a tftp server which serves from the current location
sudo dnsmasq -d --enable-tftp --port 0 --tftp-root $(pwd)
Flashing
uboot
Connect a Cisco Style RJ45 Serial Cable to the AP. The Baud Rate is 115200.
# only an example, your actual serial connection might be mounted elsewhere
picocom -b 115200 /dev/ttyUSB0
Now power the AP and connect your computer to LAN2.
Wait until Scanning JFFS2 FS: appears, press ENTER once.
Login with the following credentials:
Default Username: admin
Default Password: new2day
If those credentials don’t work let the AP boot and press the reset Button for more then 5 Seconds. That should reset the AP and restore the default settings.
Boot (PRI)-> should appear, now copy paste the following one line at a time:
setenv ramboot_openwrt "setenv ipaddr 192.168.1.22; setenv serverip 192.168.1.66; tftpboot 0x2000000 ws-ap3825i-initramfs.bin; interrupts off; bootm start 0x2000000; bootm loados; fdt resize; fdt boardsetup; fdt resize; fdt boardsetup; fdt chosen; fdt resize; fdt chosen; bootm prep; bootm go;"
setenv boot_openwrt "cp.b 0xEC000000 0x2000000 0x2000000; interrupts off; bootm start 0x2000000; bootm loados; fdt resize; fdt boardsetup; fdt resize; fdt boardsetup; fdt chosen; fdt resize; fdt chosen; bootm prep; bootm go;"
setenv bootcmd "run boot_openwrt";
saveenv
run ramboot_openwrt
The AP should now boot the initramfs OpenWRT Image.
Additional Infos
If you messed something up a reset reboots the AP.
With printenv you can print all print environment variables.
If there are multiple entries of a Variable a setenv VARIABLE_NAME should clear it.
Ram Boot
Once your booted, transfer the sysupgrade Image to /tmp on the router via scp:
scp -O ./gluon-ffda-2.5-extreme-networks-ws-ap3825i-sysupgrade.bin root@192.168.1.1:/tmp/sysupgrade.bin
wget, or another way you can think of.
Verifiy with sha256sum to check if the Image is still intact.
Flash the sysupgrade Image with the following command:
sysupgrade -n sysupgrade.bin
The AP should now reboot and after a while everything should work as expected.