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RE: Trying to build a cross compiler from linux to netbsd...



>-----Original Message-----
>From: Kai Ruottu [mailto:kai.ruottu@luukku.com]
>Sent: 03 January 2001 11:09


>---------------------- clip --------------------------------
>"Some options which only apply to building cross compilers:
>
>--with-headers=dir -- Specifies a directory which has target include
>    files. This options is required when building a cross compiler, if
>    ${prefix}/${target}/sys-include doesn't pre-exist. These include
>    files will be copied into the gcc install directory. Fixincludes
>    will be run on these files to make them compatible with gcc. "
>---------------------- clip --------------------------------
>
>can cause thoughts like (from Dave Korn):
>
>>  The words 'REQUIRED when building a cross compiler" and
>>"if $prefix/$target/sys-include doesn't exist" makes it seem like you
>>*must* use --with-headers, or put the headers into sys-include.
>
> When using my "bad English", the missing "the" in the clause would
>say clearly that the "target include files" cannot mean the standard
>C headers for the target, only some 'unspecified headers for the target'
>which need some fixing and must either be preinstalled into
>'${prefix}/${target}/sys-include', or pointed with '--with-headers'.

  Kai, your English is excellent! I think it's simply a matter of the
word 'the' being omitted/elided/implicit in that sentence; it's a somewhat
colloquial/slang kind of english usage. We tend to be a bit imprecise
with our definite articles. Of course, I cannot know for sure the intent
behind the original phrasing; this is just how I interpret it.

> My understanding for the purpose of the 'sys-include' is that it is
>the equivalent of '/usr/local/include' for a native compiler, ie. it
>was aimed for the system-specific or 3rd-party headers, searched before
>the standard C-headers (the 'sys-' comes from the 'system-specific').

  Surely unfixed headers are of no use at all ?

  There seems to be an awful lot of include directories around. I find (in
order of search path)

     $prefix/lib/gcc-lib/$target/$version/include
        - contains  fixinc'ed headers after 'make install'
     $prefix/$target/sys-include
        - contains original target headers
     $prefix/$target/include
        - nothing gets put here by gcc build/install at all.

 Now, I don't understand why we need this many directories.  It seems that
the documentation has not been kept up to date with the way things work.

> But for the 'universal case', I wouldn't suggest anybody to use the
>'--with-headers=' before the question "Why?" has been answered. There
>must be some sane reason to try to fix the standard C-headers for the
>target...

  Because libgcc needs to be built with fixed headers during the build
process before install has taken place ? 

       DaveK

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