Re: wanting to verify that a toolchain should be entirely self-contained

["Yann E. MORIN" <yann dot morin dot 1998 at anciens dot enib dot fr>]

Robert, All,

On Wednesday 28 July 2010 16:35:37 Robert P. J. Day wrote:
>   here's a question for which i'm pretty sure i know the answer, but i
> need to be absolutely sure.
>   i'm trying to cross-compile a downloaded tarball (the toolchain was
> downloaded from a vendor), and the instructions for cross-compiling
> were simply to
>   $ make CC=arm-...-gcc LD=arm-...-ld
> which is pretty standard.  but the cross compile failed almost
> immediately, complaining about a missing "curses.h" file.

As Ralf stated, the curses headers (and libs!) are not part of the
toolchain. What I do consider to be are:
- sanitised kernel headers (if targetting Linux)
- C library headers
- optionally, some internal headers from gcc, such as libstdc++ et al.

The same goes for libraries:
- the C library .so and .a files, plus any so-called start-files, namely
  crt{i,n,1].o et al.
- the internal gcc libraries: libgcc_s.so, libmudflap.so, et al.

>   the software compiles fine natively on my ubuntu 10.04 system,
> because i have all the curses-related packages installed.  but if i'm
> trying to cross-compile, is it not the responsibility of the
> *toolchain* to supply all necessary standard header files?

Well, standard is by no mean meaningful here. On a desktop PC, then
one can quite safely say that curses is standard, while on an embedded
device it is not.

What I can say is that ncurses is not a standard part of a _toolchain_.

>   as soon as i got that error, i checked where i installed the
> toolchain and noticed immediately that there was no curses.h file, and
> mentioned that.
>   someone else claimed that what i really needed to do was install the
> toolchain at /opt rather than elsewhere because the README claimed
> that the toolchain wasn't relocatable.  but i can't see how that's
> relevant.

Irrelevant, indeed. But non-sysrooted toolchains are a PITA, and you
should definitely shake your distributor off to give you a sysrooted
toolchain. And the code with that, so you can build your better own.

>   if i'm trying to cross-compile, and a C file includes a header file,
> and the toolchain doesn't supply that header file, shouldn't i expect
> the build to fail?  i certainly don't expect the cross compiler to
> wander off, looking for header files elsewhere so my position is that
> that toolchain simply isn't capable of compiling anything that
> requires curses capability because it doesn't provide a curses.h file.

The compiler should find standard toolchain includes from wherever it
was configured to find them. For the other headers, there's the -I flag
to the preprocessor. Ditto for the linker and libraries, there's -L.

Regards,
Yann E. MORIN.

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