[yocto] how does one use a prebuilt toolchain from the toolchain/ directory?

[Gary Thomas]

On 2012-07-03 03:51, Robert P. J. Day wrote:
> On Mon, 2 Jul 2012, Zhang, Jessica wrote:
>
>> On Tue, Jun 26, 2012 at 4:51 AM, Robert P. J. Day <rpjday at crashcourse.ca> wrote:
>
> ... snip ...
>
>>> 4) once i install a toolchain, how do i use it?  say i install the arm
>>> toolchain, and want to build a beagleboard image.  at what point do i
>>> source the arm toolchain environment setup file?  is that all it
>>> takes?  will the bitbake build process automatically recognize what
>>> i've done and use that toolchain?
>>
>> [JZ] Please note this toolchain is meant to be used by application
>> developers not image builders.  This toolchain is meant for cross
>> development that allows you to develop target application on your
>> host machines.  Once you source the environment-setup script, it'll
>> setup your path correctly that makes it able to find all the cross
>> development tools, e.g.
>> /opt/poky/1.2/sysroots/i686-pokysdk-linux/usr/bin/i586-poky-linux/i586-poky-linux-gcc
>> will be used for compiling your programs.
>
>    ah, i wasn't aware that the prebuilt toolchains were meant primarily
> for *app* development, not *image* development.  i already knew how to
> use them for app development, that's fairly straightforward.
>
>    which brings me back to my original curiosity -- how can i use the
> same toolchain across a number of different *image* builds?  under
> what circumstances does that make sense, and how would i do that?
>
>    say i want to configure and build images for a number of
> beagleboards, and a beaglebone, and a pandaboard, etc., all of which
> require an ARM toolchain.  if these builds can share the same
> toolchain, how can i build it once, then not have to build it over and
> over for the remaining builds?

Use SSTATE_MIRRORS to point at the sstate-cache of the first build.
This will let bitbake reuse as much as possible, including the toolchain.

I do exactly as you are proposing above and my builds for the "secondary"
targets can be as little as a couple of minutes (from scratch).

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------