UPDATE 14 MAR 2020: For discussion, see the Google group. Comments from the old WordPress site have been migrated there.
I bought and really like my Kenwood Excelon DDX9903S headunit. I had it in my WRX, and moved it to my LS430. It supports Android Auto and CarPlay, which I find really useful when driving.
However, it has a nag screen every time it boots up. This got me curious as to how it worked, and see if it could be patched to skip this disclaimer. I figured it probably ran Linux on a SoC, as pretty much everything does nowadays. So I grabbed the latest firmware for it (mine was already updated to it), and started probing.
Extract that and you get 3 folders under S_V2_7_0008_0600/:
BOOT_V2_7_0008_0600_release/ MAIN_V1_0_2758_0400/ SOC_V2_7_0008_0600/