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(g77-295.info)Cross-compiler Problems

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Cross-compiler Problems
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   `g77' has been in alpha testing since September of 1992, and in
public beta testing since February of 1995.  Alpha testing was done by
a small number of people worldwide on a fairly wide variety of
machines, involving self-compilation in most or all cases.  Beta
testing has been done primarily via self-compilation, but in more and
more cases, cross-compilation (and "criss-cross compilation", where a
version of a compiler is built on one machine to run on a second and
generate code that runs on a third) has been tried and has succeeded,
to varying extents.

   Generally, `g77' can be ported to any configuration to which `gcc',
`f2c', and `libf2c' can be ported and made to work together, aside from
the known problems described in this manual.  If you want to port `g77'
to a particular configuration, you should first make sure `gcc' and
`libf2c' can be ported to that configuration before focusing on `g77',
because `g77' is so dependent on them.

   Even for cases where `gcc' and `libf2c' work, you might run into
problems with cross-compilation on certain machines, for several
reasons.

   * There is one known bug (a design bug to be fixed in 0.6) that
     prevents configuration of `g77' as a cross-compiler in some cases,
     though there are assumptions made during configuration that
     probably make doing non-self-hosting builds a hassle, requiring
     manual intervention.

   * `gcc' might still have some trouble being configured for certain
     combinations of machines.  For example, it might not know how to
     handle floating-point constants.

   * Improvements to the way `libg2c' is built could make building
     `g77' as a cross-compiler easier--for example, passing and using
     `$(LD)' and `$(AR)' in the appropriate ways.  (This is improved in
     the `egcs' version of `g77', especially as of version 1.1.)

   * There are still some challenges putting together the right
     run-time libraries (needed by `libg2c') for a target system,
     depending on the systems involved in the configuration.  (This is
     a general problem with cross-compilation, and with `gcc' in
     particular.)