raspberrypifw binaries do not work on raspberrypi3

[makefu]

Issue description

When trying to run any of the binaries packaged in raspberrypifw (more specifically i was looking for vcgencmd) on my raspberrypi3 i get:

[nix-shell:/var/src/nixpkgs]$ vcgencmd 
bash: /nix/store/75kzz46fpnb37jv6r2pd8y7zdjg4l5mg-raspberrypi-firmware-1.20170811/bin/vcgencmd: Accessing a corrupted shared library

Steps to reproduce

nix-shell -p raspberrypifw --run vcgencmd

Technical details

• System: 18.03pre-git (Impala)
• Nix version: nix-env (Nix) 1.11.14
• Nixpkgs version: 18.03pre-git, rev: 799435b
• Sandboxing enabled: true

[Mic92]

The package does patchelf on 32-bit arm executable and set a 64-bit link-loader (on aarch64):

$ file vcgencmd
vcgencmd: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-armhf.so.3, for GNU/Linux 2.6.32, not stripped

Do we have 32-bit infrastructure for arm like we have on x86?

[dezgeg]

No, we don't. AFAIK it's more difficult than the equivalent on x86 since there's no equivalent multilib support for that in GCC (i.e. no gcc -m32) so an AArch64 -> ARM cross compiler is needed, I believe.

[dezgeg]

I changed the raspberrypifw package to only contain the firmware blobs and added a separate package raspberrypi-tools which builds the userland tools from the BSD3 source.

I tested that it compiles on AArch64, but don't have the hardware on hand right now (only RPi 1) so please test and close if it works now.

[dezgeg]

On IRC I got a test report that the vchiq module isn't working out-of-the-box on mainline, but there are kernel patches floating/merged that will make it work on either 4.17 or 4.18.

[florianjacob]

This seems to work now as of 18.09 and kernel 4.18.16:

$ sudo vcgencmd measure_temp
temp=37.6'C

Sidenote: Requires root access. Without, this fails with a misleading error message:

$ vcgencmd
VCHI initialization failed