OpenWrt on Cisco ISR 4400 series routers

For Developers
1

I hope you are doing fine.
For the past few months i have been working on this Getting an old Cisco 2911 running with OpenWrt to get OpenWrt or at least a linux kernel running on Cisco 2900 series MIPS routers. I had a tough time, especially when building the device tree and device init, but i got something working at least.

Now, as ISR 4400 series routers are becoming incredibly cheap, i ordered a pair for $50 each of ISR 4431. Those are x86 based, so it should be much easier to get stuff built and running for this platform. As my major concern for MIPS was the annoying cross-compiling process for Octeon. I expect this to be much easier. Also the verification process and checksumming for running ELF executables is still known, so should be no issue either.

Are there any efforts already into this direction?
Otherwise i will keep this thread as a tracker for my work on this.

BR,

2

Do you have a PR or branch for the old 2911 patches? Would be very interesting to see that.

3

It will be a tough call, modern rommon is on a very strong side of verified boot. Probably you need some hidden diagnostic command to execute anything not blessed by cco.

4

Yeah i think so too.
That's my first attempt of just plain loading of some generic x86 openwrt image.

rommon 21 > dir usb0:

0   776534376 -rw-     isr4300-universalk9.17.12.04b.SPA.bin
0   126353408 -rw-     openwrt-24.10.0-rc7-x86-64-generic-squashfs-combined.img
rommon 22 > boot usb0:openwrt-24.10.0-rc7-x86-64-generic-squashfs-combined.img
Located openwrt-24.10.0-rc7-x86-64-generic-squashfs-combined.img
##############################################################################

Unsupported package header version (1388216445)
Failed to boot file usb0:openwrt-24.10.0-rc7-x86-64-generic-squashfs-combined.img
5

Try initramfs kernel package...
and binrwalk cco bin file, it may not even be Linux

6

Thanks!
Yeah it's a Linux image with version 5.15, the IOS-XE one.
But unfortunately i think we will hit a wall regarding the RSA signing of the image.