Re: Issues w/ cross-compiling

[Ralf Wildenhues]

* Philip A. Prindeville wrote on Tue, Jul 08, 2008 at 11:44:08PM CEST:
> Ralf Wildenhues wrote:
>> If you have a way to actually execute code on the compile
>> system (get binfmt to execute 'elksemu $binary' should be
>> possible), then you can avoid compile-only tests and make
>> AC_COMPUTE_INT use the cheaper execution test.

> What about using 'nm'?  Generate an object file (or intermediate object  
> file) with two adjacent symbols (packed) of the same size, and subtract  
> the difference in addresses?

Well, having to rely on 'nm' to even exist is a bit of a pain.
For example, the bin86 package that is used along with bcc has
the program named nm86, which a tool check would not have found
automatically.  Then, the nm output format is poorly standardized
(see Libtool), relying on the order a compiler outputs symbols is
AFAIK not safe.  Plus, packing would lead to the wrong solution
(AC_CHECK_SIZEOF is intended to return the result that sizeof would,
not that sizeof of the packed version of the type would).

The proposed ideas of fixing AC_LANG_BOOL_COMPILE_TRY(C) may be pursued.
Or bcc fixed.  Or you may be able to get by with binfmt_misc (this is
actually described in a README for elks-libc).  There are however more
issueswhen using that.  For one, the Autoconf testsuite test
  172: C keywords

causes bcc to get stuck in an endless loop outputting an error, which
just managed to fill my work partition...

Cheers,
Ralf