[yocto] examples / docs on utilizing an external toolchain

[Kumar Gala]

>>>>>> http://bugzilla.pokylinux.org/show_bug.cgi?id=1323
>>>>>> 
>>>>>> My question still stands even w/o it being in formal docs.
>>>>> 
>>>>> FWIW, POKYMODE was replaced by TCMODE as part of the OE-Core changes.
>>>>> I'd be interested to know where we've missed the references to it and
>>>>> get to get those references fixed.
>>>> 
>>>> Ok, but how does one use TCMODE?  :)
>>>> 
>>>> is there an example around anywhere?
>>> 
>>> I'll explain on the condition that someone actually documents this ;-).
>>> 
>>> TCMODE determines which of the files in
>>> meta/conf/distro/include/tcmode-* is used. It defaults to "default" and
>>> our default toolchain definition is in tcmode-default.inc.
>>> 
>>> There is another example there which is "external-csl2008q3". As you can
>>> see from the tcmode-external-csl2008q3 file, it sets up the system to
>>> use an external toolchain instead.
>>> 
>>> So you can define one of these files in your layer and then the system
>>> can select alternative toolchain configurations.
>>> 
>>> Does that help? :)
>>> 
>>> There is a similar TCLIBC variable which controls which libc is used
>>> (eglibc or uclibc).
>> 
>> Yes that helps.  So it looks as if today there is not a means to point
>> to SDK prebuilt toolchain via this means.
> 
> We have supported this in the past but it got messy and I'd really
> prefer people to use sstate for this.
> 
> You obviously can use the SDK toolchain as a prebuilt external toolchain
> though since its no different from any other external toolchain.


What got mess about it?  Seems like a poky built sdk toolchain should work as an external toolchain w/o too much issue.

- k