[Buildroot] non-standard architecture targets

Yann E. MORIN yann.morin.1998 at free.fr
Sun Feb 10 16:33:41 UTC 2013

Martin, All,

On Sunday 10 February 2013 martin krastev wrote:
> I am trying to get buildroot (buildroot-2012.11.1) to produce a cross
> toolchain (x86_64 -> powerpc) of a non-standard target triplet (if
> it's still called that way).

We call them tuples, rather than triplets, as they can have four parts.

> I am currently getting
> "powerpc-buildroot-linux-uclibc", and I would like to extend that to
> "powerpc-buildroot-linux-uclibc-paired" or
> "powerpc-buildroot-linux-paired-uclibc" - generally anything following
> the powerpc*-*-linux*paired* pattern.
> What is the natural way to set this up in buildroot?

That is not posible, as those are not valid tuple.
A tuple is what describes the target, and needs to be constructed
in a very precise (and inflexible) format:


  - 'arch' is the architecture part of the tuple (arm, armeb, mipsel,
    i386, powerpc...)
  - 'vendor' is an almost-free-form part (but does not accept spaces
    nor dashes, and globally, any other weird chars)
  - 'abi' is the ABI part, for example: elf, eabi, gnueabi, uclibc...
  - 'kernel' is the name of the kernel, eg. linux

Not all combinations of {arch,vendor,{os,}abi} are valid.

To check if a tuple is valid, use: ./support/gnuconfig/config.sub

    $ ./support/gnuconfig/config.sub powerpc-buildroot-linux-paired-uclibc
    Invalid configuration `powerpc-buildroot-linux-paired-uclibc': machine
    `powerpc-buildroot-linux-paired' not recognized

If your tuple is valid, but non-canonic, config.sub will output the
canonic form of the tuple, eg:

    $ ./support/gnuconfig/config.sub powerpc-linux

Unfortunately, I am not aware of a central authoritative list of valid
tuples, and the config.{guess,sub} scripts are the only authoritative
reference for building tuples, AFAIK.

However, if you want to differentiate your tuples, you can use the
vendor-part of the tuple (typically, 'buildroot' in tuples above).
This not possible with Buildroot: toolchains built with Buildroot
will always have 'buildroot' as the vendor-part. Some other toolchain
builders may allow you to override the vendor-part (eg. crosstool-NG
does have that possibility).

Yann E. MORIN.

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