Identifying a Raspberry Pi host with configure - linux

Question

I work on a cross-platform project, and recently added support for the Raspberry Pi. The project, to make sure it is available at as wide as possible audience, has a premake, a cmake and an autotools build system. I have set up cross-compilation for the RPi, and everything works great.
Recently, I also set up a Raspberry Pi VM (Until I get a real RPi) trying to build the library. From Linux, I run './configure --host=arm-raspberry-linux-gnueabihf', and configure takes it from there. On the RPi however (Rasbian 7), the default host found by config.guess is 'armv61-unknown-linux-gnueabihf'. For that reason, even natively on the Pi, I have to run './configure --host=arm-raspberry-linux-gnueabihf'. So, my question sums up to this:
Currently, I currently have something like this in my configure script:
case "$host" in
armv61-unknown-linux-gnueabihf)
if [[ -f /usr/bin/rpi-update ]]; then
on_raspberry=yes
fi
;;
## other hosts here
esac
So, my question sums up to this:
Is 'armv61-unknown-linux-gnueabihf' only reported on the Raspberry Pi? If not, how can configure make sure that it is really on RPi? Is checking for rpi-update sufficient? Do different distros (Arch Linux, Pidora, ...) also have rpi-update?
Are there any other possible host triplets like this that are reported by different versions of the Pi?
Thanks in advance

Answer 1

Is 'armv61-unknown-linux-gnueabihf' only reported on the Raspberry Pi?
Other platforms could use that as well.
If not, how can configure make sure that it is really on RPi?
It can't really (e.g. running it on a RPi VM). configure is just a shell script.
Is checking for rpi-update sufficient?
See above.
Do different distros (Arch Linux, Pidora, ...) also have rpi-update?
Current Pidora and Arch images don't have /usr/bin/rpi-update. Neither does old Rasbpian images at least as far back as 10 Aug 2012.
Are there any other possible host triplets like this that are reported by different versions of the Pi?
There are 3 triplets for the RPi cross compilers, so it would not be surprising if there were others.
EDIT: so basically what is wanted is a way for configure to detect when it's building on a Raspberry Pi. Easy as pie:
configure.ac
# need to detect build...
AC_CANONICAL_BUILD
...
AC_MSG_CHECKING([if build is on Raspberry Pi])
# The test for 'BCM2708' might be sufficient,
# but the presence of Serial is definitely part of
# the Pi firmware for codec licensing.
# See this thread
# <http://www.raspberrypi.org/phpBB3/viewtopic.phpf=29&t=28304&p=252357#p251536>.
AS_CASE("$build",
[arm*-*-linux*],
[on_rpi=`awk -v r=0 '/^Hardware#<:# \t#:>#+:#<:# \t#:>#+BCM2708/ { ++r;} /^Serial#<:# \t#:>#+:/ { ++r; } END { print ((r > 1) ? "yes" : "no");}' /proc/cpuinfo`],
[on_rpi="no"])
AC_MSG_RESULT($on_rpi)
Detects on Raspbian, Pidora, should work on Arch. Arch doesn't seem to include a compiler in its current install image, so configure failed when I tried it. All detected build as armv6l-unknown-linux-gnueabihf when running ./configure. I have not tried this on any kind of RPi emulator or VM.

Answer 2

BCM2708 in /proc/cpuinfo might be unique for RPi.
From File /proc/cpuinfo
Processor : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS : 697.95
Features : swp half thumb fastmult vfp edsp java tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xb76
CPU revision : 7
Hardware : BCM2708
Revision : 000d
Serial : 00000000db690cb4