Re: [patch] help for cross compiling lua

["Dirk Feytons" <dirk.feytons@...>]

On Wed, Mar 5, 2008 at 8:26 PM, John E Hein <jhein@timing.com> wrote:
> Dirk Feytons wrote at 14:42 +0100 on Mar  5, 2008:
>
>   > Another classic way is the use of a CROSS_COMPILE variable.
>   > The Makefile then looks something like this:
>   > CC=$(CROSS_COMPILE)gcc
>   > AR=$(CROSS_COMPILE)ar
>   > ...
>   >
>   > By just setting CROSS_COMPILE to e.g. "mips-linux-uclibc-" you can do
>   > cross compilation while not setting the variable uses your host
>   > compiler (provided your toolchains are appropriately named).
>
>  I like the idea from a simplicity standpoint (just set one variable
>  and be done with it).
>
>  Unfortunately, it's not very standard _as far as I know_.  For
>  instance, autoconf doesn't generate support cross compiling that way.
>  It just defines CC, etc., which you can override.  However... it does
>  support --host=<prefix> which is basically the same as your
>  CROSS_COMPILE suggestion... except lua doesn't have a 'configure'
>  stage before calling make - i.e., there's no "lua way" to configure
>  the makefile before running make (again, as far as I know).

Lua has the advantage that it is ANSI C and so small that it is very
easy to just write a custom Makefile for whatever build setup you are
using.
They better don't add autoconf stuff; the ./configure step would
probably take longer than the actual compilation :)

>  autoconf is not a standard, you say?  Well it's a bit of a de facto
>  standard, unfortunately.  But I agree.  Basing Makefile support for
>  cross compiles on what autoconf does is only one factor one might
>  consider.

Autoconf is not really standard in the embedded world from what I've
seen (which is not that much to be honest; we don't have many 3rd
party components).

>  If lua adds something like the prefix above, it won't bother me.  I'll
>  just add CROSS_COMPILE to my cross build environment in addition to
>  AR, CC, RANLIB, STRIP, etc.  What's one more variable?

One advantage of CROSS_COMPILE is that it doesn't have any effect if
you don't use it.

>  If lua does go that route, as far as naming the prefix, I don't know
>  of anything that uses that exact name, CROSS_COMPILE.  Indeed I
>  don't know of any software off the top of my head which uses
>  the prefix method.  But there's lots of software out there.
>
>  Does anyone have any good examples of software packages that use
>  such a prefix method?

The Linux kernel :)

>   > In any case, adding ARFLAGS is certainly useful.
>
>  Indeed.  Applying the ARFLAGS patch is a good fix regardless, I think.

-- 
Dirk