Big-endian mode supported for Raspberry Pi [0-3] with bootable images available

[Rin Okuyama <rokuyama.rk%gmail.com@localhost>]

I'm happy to announce that big-endian mode has been supported for
Raspberry Pi [0-3] in -current. Bootable disk images are available in
official daily snapshots. You can enjoy aarch64eb/armeb world on your
Pi's by just flashing these images to microSD!

vchiq(4) and vcaudio(4) are not supported in big-endian mode. This
requires heavy modifications to third party source codes. Anyway, we
will switch to vc4 drm driver, hopefully soon.

Pi 4 is not supported also. It needs ACPI, but acpica does not support
big-endian environments. This is really headache...

Other devices and features are supported in a similar manner as in
little-endian modes. Please tell me if you find endian-related bugs.

Available architectures and supported models are:

- aarch64eb

Pi 3 is supported by GENERIC64 kernel.

Bootable image is:
http://nycdn.netbsd.org/pub/NetBSD-daily/HEAD/latest/evbarm-aarch64eb/binary/gzimg/arm64.img.gz

- earmv7hfeb and earmv7eb

Pi [2-3] are supported by GENERIC kernel.

Bootable image for earmv7hfeb is:
http://nycdn.netbsd.org/pub/NetBSD-daily/HEAD/latest/evbarm-earmv7hfeb/binary/gzimg/armv7.img.gz

- earmv6hfeb and earmv6eb

Pi [0-1] are supported by RPI, and Pi 2 is supported by RPI2 kernel.

Bootable image for earmv6hfeb is:
http://nycdn.netbsd.org/pub/NetBSD-daily/HEAD/latest/evbarm-earmv6hfeb/binary/gzimg/rpi.img.gz

Enjoy,
rin