[yocto] examples / docs on utilizing an external toolchain

[Gary Thomas]

On 2011-08-04 08:49, Richard Purdie wrote:
> On Wed, 2011-08-03 at 23:59 -0500, Kumar Gala wrote:
>> On Aug 3, 2011, at 10:12 AM, Richard Purdie wrote:
>>
>>> On Wed, 2011-08-03 at 09:50 -0500, Kumar Gala wrote:
>>>> On Aug 3, 2011, at 9:22 AM, Richard Purdie wrote:
>>>>
>>>>> On Wed, 2011-08-03 at 09:04 -0500, Kumar Gala wrote:
>>>>>> Bug submitted:
>>>>>>
>>>>>> 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.

That would be great, if only it worked for this purpose.  Sadly, I've not
had much luck with sharing toolchains like this.

Here's my problem - I have a number of different target platforms (MACHINE),
all of which are really the same ARM SoC (OMAP/3530==armv7a).  When I try
to share the sstate between them, the toolchain always rebuilds from scratch.
A lot of other packages do seem to share state properly, e.g. busybox built
for these platforms uses sstate well, but not so with toolchains.

Is there any way for this to work?  I'd love to be able to hand my customers
a set of sstate files for the things they don't really need to rebuild and
the toolchains are a giant part of it.  If this should work and the current
failures a bug, I'll report it as such.

Thanks

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