Let’s start with tools that we need to just build the OS for ARM. First clone official inferno os repository from google code repository:

1# hg clone https://code.google.com/p/inferno-os/

What we need to move further? We need the ARM cross compiler, linker, etc. For this, let’s just compile inferno targeting mac as host (we are on mac now, so we will get hosted inferno for mac as result):

 1# cd inferno-os/
 2# INF_ROOT=`pwd` perl -i -pe 's/^ROOT=.*/ROOT=$ENV{INF_ROOT}/m' mkconfig
 3# perl -i -pe 's/^SYSHOST=.*/SYSHOST=MacOSX/m' mkconfig
 4# perl -i -pe 's/^OBJTYPE=.*/OBJTYPE=386/m' mkconfig
 5# sh makemk.sh
 6# PATH=`pwd`/MacOSX/386/bin:$PATH mk nuke
 7# PATH=`pwd`/MacOSX/386/bin:$PATH mk install
 8… waiting just few minutes … 
 9# ls MacOSX/386/bin/
100a         2l         8l         iar        ksize      ms2        tc
110c         5a         acid       idea       kstrip     ndate      va
120l         5c         asm        inm        limbo      qa         vc
131a         5coff      c2l        iyacc      md5sum     qc         vl
141c         5cv        data2c     ka         mk         ql
151l         5l         data2s     kc         mk.save    sqz
162a         8a         emu        kl         mkext      srclist
172c         8c         ftl        kprof      mkppcimage styxtest

Yes! Now we have all needed cross-platform tools for building Inferno OS for ARM, see 5c – C compiler, 5a – ARM assembler, 5l – ARM linker. Let’s check ARM asm generated:

1# export PATH=`pwd`/MacOSX/386/bin:$PATH 
2# echo "int main() { return 123; }" >tmp.c && 5c -S tmp.c && rm tmp.c
3	TEXT	main+0(SB),0,$0
4	MOVW	$123,R0
5	RET	,
6	RET	,
7	END	,