Unclear Configure Options

[Ian Lance Taylor]

booleandomain <booleandomain@gmail.com> writes:

> For example, what does the --with-local-prefix do? I read you should
> specify a directory, where the default is /usr/local. I also read it
> is not a directory where gcc will install files to, but it is a
> directory gcc will read files from. I wonder what gcc likes to find
> inside of it. I also wonder if it is possible to use something like
> --without-local-prefix.

Given --with-local-prefix=/my/local/prefix, gcc will search for header
files in /my/local/prefix/include.  That is, given #include "foo.h", gcc
will check for /my/local/prefix/include/foo.h.  It will search there
before it searches /usr/include.

You can't say --without-local-prefix, but you can say, e.g.,
--with-local-prefix=/dev/null.


> Another option I don't fully understand is --with-sysroot, that is
> used only when cross-compiling. It also accepts a directory path. What
> does gcc likes to find inside it? Linux kernel headers perhaps? Glibc
> libraries?

--with-sysroot should point at a directory tree which looks exactly like
an installed system.  E.g., given --with-sysroot=/my/sysroot, you should
have a directory /my/sysroot/usr/include which holds header files, you
shoudl have /my/sysroot/lib and/or /my/sysroot/usr/lib holding
libraries, etc.


> I also don't know if it is possible to delete the specified
> directories after gcc installation, or if gcc must be able to access
> them even after installation has been done.

In general gcc is fine if directories do not exist.  Of course, it's a
problem if gcc can not find the files that it needs.

Ian