[yocto] Questions regarding adding a new llvm based cross-compiler

[Cody P Schafer]

On Fri, Oct 17, 2014 at 1:48 PM, Martin Jansa <martin.jansa at gmail.com> wrote:
> On Fri, Oct 17, 2014 at 09:07:19AM +0100, Paul Barker wrote:
>> On 16 October 2014 18:46, Cody P Schafer <dev at codyps.com> wrote:
>> > Hi all,
>> >
>> > I'm working on creating a layer for the rust compiler (which uses
>> > llvm) and was wondering if there were any best practices and/or
>> > examples people could point me at.
>
> Are you using llvm recipes from meta-oe (or at least starting from
> them)?

I wasn't. Rust packages a particular llvm version already (and ties it
into it's build scripts). I'm planning on just using that one.

> I haven't tried it yet, but I've asked Servo developer, how they do
> cross-builds and he said that it's really simple with Rust and Cargo,
> which support cross-compilation by design.

Well:

>From what I've found, crossbuilds work fine if you're using one of a
small set of blessed triples (ie: not arm-poky-linux-gnueabi, but
arm-unknown-linux-gnueabihf), and you don't set any special
CFLAGS/LDFLAGS variables (which oe does).
And the infrastructure is not in place to allow packagers to easily
add/use different triples and "linkers" (rustc calls gcc/cc to link
it's programs, and as a result needs to know where it is).