[aur-general] Conventions on packages for cross-compiling

[Allan McRae]

Vojtech Horky wrote:
> Allan McRae napsal(a):
>> Vojtech Horky wrote:
>>> 2009/10/13 Allan McRae <allan at archlinux.org>:
>>>  
>>>> Vojtech Horky wrote:
>>>>   
>>>>> 2009/10/8 bardo <ilbardo at gmail.com>:
>>>>>
>>>>>     
>>>>>> 2009/10/7 Vojtech Horky <vojta.horky at seznam.cz>:
>>>>>>
>>>>>>       
>>>>>>> Hi all,
>>>>>>> I am seeking advice how to write correct PKGBUILDs for 
>>>>>>> cross-compilers.
>>>>>>>
>>>>>>> The thing I am not sure about is where to install them.
>>>>>>> Trouble is that even the binary packages use different locations 
>>>>>>> and I
>>>>>>> haven't found any other source where to get information from (for
>>>>>>> example, cross-arm-wince-cegcc-binutils uses prefix /opt/cegcc/ 
>>>>>>> while
>>>>>>> mingw32-gcc uses /usr).
>>>>>>> So, which location would you recommend/is better?
>>>>>>>
>>>>>>>           
>>>>>> Some time ago I asked the same question about my AVR toolchain, 
>>>>>> which
>>>>>> is now in [community]. I think the original thread can be 
>>>>>> interesting
>>>>>> to you:
>>>>>>
>>>>>> http://mailman.archlinux.org/pipermail/aur-general/2008-January/thread.html#611 
>>>>>>
>>>>>>
>>>>>>
>>>>>>       
>>>>>>> Another thing - is the correct naming convention
>>>>>>> 'cross-<arch>-<pkgname>'?
>>>>>>>
>>>>>>>           
>>>>>> As you see, I just stuck with the '-arch' postfix =)
>>>>>>
>>>>>> Corrado
>>>>>>
>>>>>>
>>>>>>         
>>>>> Hi,
>>>>> first of all - thanks everybody for the suggestions and the links.
>>>>>
>>>>> I read them through, (again and again) looked around how others do it
>>>>> and finally decided to really write that wiki page as Loui 
>>>>> proposed. I
>>>>> put the guidelines proposal on
>>>>>
>>>>> http://wiki.archlinux.org/index.php/Cross_Compiling_Tools_Package_Guidelines_Proposal 
>>>>>
>>>>> I and would be really glad if someone would find some time to read it
>>>>> and express his opinion.
>>>>>       
>>>> I have been looking into cross-compilers a lot lately, and I think 
>>>> the best
>>>> place to put _all_ their files is /usr/lib/cross-*-*-* and then 
>>>> symlink
>>>> needed stuff or add wrapper scripts in /usr/bin/.  This is more FHS
>>>> compliant than the /usr/i486-mingw32 that is used in mingw32 and 
>>>> /usr/avr in
>>>> the avr one.
>>>>     
>>> I agree that it is more FHS compliant but I would prefer to have files
>>> directly (i.e. no symlinks) where they are supposed to be (e.g. put
>>> executables into /usr/bin rather than symlinking them from
>>> /usr/lib/cross*).
>>>   
>>
>> I found an issue with just using /usr directly...  see below.
>>
>>>> Does your proposed build process lead to any "interesting"
>>>> directories in /usr?
>>>>     
>>> No. But sometimes a small hack is needed (e.g. the tooldir settings
>>> for binutils). Possible conflicts are solved by adding architecture
>>> prefix and duplicate files are not installed at all (e.g. man pages or
>>> READMEs).
>>> BTW, the MIPS cross-compilers
>>> (http://aur.archlinux.org/packages.php?O=0&K=cross-mips) now follow
>>> the proposed guidelines from the wiki.
>>>   
>>
>> Are there no headers needed for mips?  Seems weird...
> Some headers are installed into 
> /usr/lib/gcc/mipsel-linux-gnu/4.3.2/include/ and these are found 
> correctly and do not interfere with the native gcc:
> ~$mipsel-linux-gnu-cpp -v
> ...
> #include "..." search starts here:
> #include <...> search starts here:
>  /usr/lib/gcc/mipsel-linux-gnu/4.3.2/include
>  /usr/lib/gcc/mipsel-linux-gnu/4.3.2/include-fixed
> End of search list.
> ~$cpp -v
> ...
> #include "..." search starts here:
> #include <...> search starts here:
>  /usr/local/include
>  /usr/lib/gcc/x86_64-unknown-linux-gnu/4.4.1/include
>  /usr/lib/gcc/x86_64-unknown-linux-gnu/4.4.1/include-fixed
>  /usr/include
> End of search list.
>
> > and this may be
>> an issue with other cross compilers.  If the mingw headers go in 
>> /usr/include there will be lots of conflicts.
> Probably I am completely wrong, but won't the headers be the same for 
> all architectures? Of course, except for the very low-level macros 
> that are stored outside /usr/include anyway (I mean those files in 
> /usr/lib/gcc/<arch>/include/).

You are assuming that the same C library is being used.  For example, 
the mingw32 library include files are very different.

Allan