[yocto] Cross compiler which runs on the target architecture.

[Peter Saunderson]

Hi,

I have seen a brief IRC chat 
(https://www.yoctoproject.org/irc/%23yocto.2013-09-23.log.html talking 
about https://github.com/nathanrossi/meta-parallella) about this 
question but nothing much else so this is an attempt to get more public 
feedback on this request.

I am trying to build a cross compiler that runs on the target processor 
and a cross compiler that runs on the host processor so that I can build 
code for a third processor (Epiphany).  If you want examples of the 
traditional way to build this compiler look at 
https://github.com/adapteva/epiphany-sdk epiphany-gcc epiphany-newlib 
epiphany-binutils... The end result would be a set of recipes that run 
on a pc build machine that build both arm code for the interim target 
and epiphany code for the final target and provides an SDK for the pc 
that enables you to cross compile for both arm and epiphany.

As I am just starting to look at this I would like to know what size of 
task I am up against!  My initial efforts based on review of 
poky/meta/recipes-devtools/binutils etc seem to suggest that I have to 
modify at least ${HOST_PREFIX}, ${TARGET_PREFIX}, ${TARGET_ARCH} etc for 
my epiphany-??? recipes so that the I can install the compiler in a 
suitable location with a suitable prefix, the IRC chat indicates that 
there are more things to consider also.

The question I have is about how easy it will be to use existing recipes 
for existing compiler / binutils etc... or is this likely to end up as a 
completely new set of recipes from the ground up because the existing 
recipes cant cope with building cross / cross compilers where there are 
three processors to consider (host (intel based pc), interim target 
(arm) and final target (epiphany)), or at least a lot of changes in the 
existing recipes to cope with something like TARGET_TARGET_ARCH = 
${TARGET_ARCH}_${FINAL_TARGET_ARCH}??

Thanks in advance for any comments.

Peter.