We saw this yesterday and thought it could potentially be a joke, so we didn't bother posting it. However, it looks like it's still true today.
The folks at Magic Lantern have booted the Linux kernel on a Canon DSLR.
FROM MAGIC LANTERN:
We took the latest Linux kernel (3.19) and did the first steps to port it. As we have nearly zero experience with kernel development, we didn't get too far, but we can present a proof of concept implementation that boots the Linux kernel 3.19 on Canon EOS DSLR cameras!
- It is portable, the same binary runs on all ML-enabled cameras (confirmed for 60D, 600D, 7D, 5D2 and 5D3)
- Allocates all available RAM
- Prints debug messages on the camera screen
- Sets up timer interrupts for scheduling
- Mounts a 8 MiB ext2fs initial ramdisk
- Starts /bin/init from the initrd
- Shis init process is a selfcontained, libc-less hello world
- Next step: build userspace binaries (GUI, etc)