20.04 on mac M1

[Jerry Geis]

On Wed, Oct 13, 2021 at 3:59 PM Colin Watson <cjwatson at ubuntu.com> wrote:

> On Wed, Oct 13, 2021 at 03:41:56PM -0400, Jerry Geis wrote:
> > Hi Paul - thanks for the reply..  So I have
> > /usr/alpha-linux-gnu/include/sys/io.h
> >
> > but it must not be actually included when I compile as a standard include
> > directory ???
> >
> > if I add the -I/usr/alpha-linux-gnu/include to the compile - now - that
> > does work.   Thanks!  Not sure why its not picking it up automatically.
>
> Because Alpha is a totally different CPU architecture from ARM, and you
> only have that file because you installed a package for cross-compiling
> programs to run on Alpha.  If using that search path works for you, it
> can only be by luck: the architecture-specific definitions it gives you
> will be entirely wrong, because they're designed for a completely
> different kind of computer.  I very strongly recommend against hacking
> this search path into your build process.
>
> <sys/io.h> only exists at all on a few architectures (Intel x86, IA64,
> and Alpha).  A program that relies on it is simply not going to work on
> ARM without more substantial porting work.  (Of course, if the program
> you're trying to build isn't very carefully-written, then it's always
> possible that it includes this header but doesn't actually use it.)
>
> --
> Colin Watson (he/him)                              [cjwatson at ubuntu.com]
>
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Thanks Colin - Sounds like I may have to tweak this 25 year old program.

Jerry
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