[U-Boot] How do I tell buildman to use a /specific/ toolchain?

[Stephen Warren <swarren@wwwdotorg.org>]

On 10/04/2015 10:38 AM, Simon Glass wrote:
> Hi Stephen,
> 
> On 3 October 2015 at 20:20, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> On 10/03/2015 08:30 AM, Simon Glass wrote:
>>> Hi Stephen,
>>>
>>> On 2 October 2015 at 00:27, Stephen Warren <swarren@wwwdotorg.org> wrote:
>>>> On 10/01/2015 04:59 PM, Simon Glass wrote:
>>>>>
>>>>> Hi Stephen,
>>>>>
>>>>> On Wednesday, 23 September 2015, Stephen Warren <swarren@wwwdotorg.org>
>>>>> wrote:
>>>>>>
>>>>>>
>>>>>> Simon,
>>>>>>
>>>>>> I have 3 different ARM toolchains installed into /usr/bin via distro
>>>>>> packages. How do I tell buildman which of those to use?
>>>>>>
>>>>>> I had originally thought that ~/.buildman's [toolchain] section contained
>>>>>> CROSS_COMPILE-like values, so I tried:
>>>>>>
>>>>>>> [toolchain]
>>>>>>> root: /
>>>>>>> arm0-not-installed: arm-none-gnueabi-
>>>>>>> arm1: arm-none-eabi-
>>>>>>> arm2: arm-linux-gnueabihf-
>>>>>>> arm3: arm-linux-gnueabi-
>>>>>>> arch64: aarch64-linux-gnu-
>>>>>>>
>>>>>>> [toolchain-alias]
>>>>>>> arm: arm1
>>>>>>> aarch64: aarch64
>>>>>>
>>>>>>
>>>>>>
>>>>>> (I intended to change the "arm: arm1" line to point at arm1/2/3 based on
>>>>>> which I wanted to use at a particular time).
>>>>>>
>>>>>> However, running "buildman --list-toolchains" and re-reading the docs
>>>>>> shows me that the [toolchain] values are absolute directories that buildman
>>>>>> searches for files named *-gcc:
>>>>>>
>>>>>>>     - scanning path 'arm-none-gnueabi-'
>>>>>>>        - looking in 'arm-none-gnueabi-/.'
>>>>>>>        - looking in 'arm-none-gnueabi-/bin'
>>>>>>>        - looking in 'arm-none-gnueabi-/usr/bin'
>>>>>>
>>>>>>
>>>>>>
>>>>>> If buildman finds multiple toolchains, there doesn't seem to be a way to
>>>>>> tell it which one to use. Am I missing something?
>>>>>>
>>>>>> I suppose a solution wouuld be to move the compiler binaries into
>>>>>> different separate directories, and only list one of those directories in
>>>>>> ~/.buildman. However, I can't do that for distro-packaged toolchains (well,
>>>>>> I suppose I could manually mv everything all over the place, but that's
>>>>>> really fragile since it'd break any time the package got upgraded or removed
>>>>>> and re-installed).
>>>>>>
>>>>>> I think it makes sense to add new syntax into ~/.buildman to specify
>>>>>> "don't do automagical searching, just use this CROSS_COMPILE value that I
>>>>>> say". Does that sound reasonable? Automagic stuff makes for great defaults,
>>>>>> but if it can't be overridden, it sucks when you actually know what you
>>>>>> want.
>>>>>
>>>>>
>>>>> Yes I think it would be fine to add an option to use CROSS_COMPILE (of
>>>>> course it would fail if you tried to build the board with the wrong
>>>>> arch).
>>>>
>>>>
>>>> I wasn't necessarily looking for buildman to pick up the CROSS_COMPILE
>>>> environment variable, although that would be a simple solution for
>>>> single-arch builds at least. My mention of CROSS_COMPILE immediately above
>>>> was re: using values that are formatted in the same way as the CROSS_COMPILE
>>>> environment variable would be, rather than directory names, in the config
>>>> file. In other words, the example content I showed above.
>>>>
>>>>> The option other option at present is -G which lets you use multiple
>>>>> .buildman files. You could have one of these for each toolchain.
>>>>
>>>>
>>>> I don't think that gets me what I want. As far as I can tell, the buildman
>>>> config file contains a list directories to search within, yet if I have 3
>>>> toolchains in a single directory, there's no way to select which one I want
>>>> to use, is there?
>>>>
>>>> In other words, a config file that contains:
>>>>
>>>> [toolchain]
>>>> distro-packages: /usr/bin
>>>>
>>>> ... finds the following toolchains:
>>>>
>>>> [swarren at swarren-lx1 u-boot]$ ./tools/buildman/buildman \
>>>>         --list-tool-chains
>>>> Scanning for tool chains
>>>>    - scanning path '/usr/bin'
>>>>       - looking in '/usr/bin/.'
>>>>          - found '/usr/bin/./arm-linux-gnueabi-gcc'
>>>>          - found '/usr/bin/./arm-linux-gnueabihf-gcc'
>>>>          - found '/usr/bin/./arm-none-eabi-gcc'
>>>> (That's 3 AArch32 toolchains found)
>>>>          - found '/usr/bin/./winegcc'
>>>>          - found '/usr/bin/./aarch64-linux-gnu-gcc'
>>>>          - found '/usr/bin/./gcc'
>>>>          - found '/usr/bin/./c89-gcc'
>>>>          - found '/usr/bin/./x86_64-linux-gnu-gcc'
>>>>          - found '/usr/bin/./i586-mingw32msvc-gcc'
>>>>          - found '/usr/bin/./c99-gcc'
>>>>       - looking in '/usr/bin/bin'
>>>>       - looking in '/usr/bin/usr/bin'
>>>> Tool chain test:  OK
>>>> Tool chain test:  OK
>>>> Tool chain test:  OK
>>>> Tool chain test:  OK
>>>> Tool chain test:  OK
>>>> Tool chain test:  OK
>>>> Tool chain test:  OK
>>>> Tool chain test:  OK
>>>> Tool chain test:  OK
>>>> Tool chain test:  OK
>>>> List of available toolchains (7):
>>>> aarch64   : /usr/bin/./aarch64-linux-gnu-gcc
>>>> arm       : /usr/bin/./arm-linux-gnueabi-gcc
>>>> (Buildman chose that one, and I think I have no control over that?)
>>>> c89       : /usr/bin/./c89-gcc
>>>> c99       : /usr/bin/./c99-gcc
>>>> i586      : /usr/bin/./i586-mingw32msvc-gcc
>>>> sandbox   : /usr/bin/./winegcc
>>>> x86_64    : /usr/bin/./x86_64-linux-gnu-gcc
>>>
>>> I wonder if we need an option to specify the full path and avoid the search?
>>>
>>> Maybe [toolchain-prefix] ?
>>
>> Yes, that sounds like exactly what I was hoping for.
> 
> OK - would you like to do a patch?

I was hoping you could; I had looked into the toolchain selection
algorithms in buildroot quite a while back and wasn't able to work out
how to implement a feature like that.