Hey all
I don't really understand the meaning and difference of --with-sysroot
and --with-build-sysroot. From http://gcc.gnu.org/install/configure.html:
> --with-sysroot=dir
> Tells GCC to consider dir as the root of a tree that contains a
> (subset of) the root filesystem of the target operating system.
The GCC that is used to compile the current GCC source or the final
compiled GCC later at runtime? I assume for both.
> Target
> system headers, libraries and run-time object files will be searched
> in there.
I'm compiling a build=i686-pc-linux-gnu host=i686-pc-linux-gnu
target=i686-pc-linux-gnu. I put glibc and glibc-devel into sysroot. This
worked with GCC 4.2 but fails with GCC 4.3 because "linux/limits.h"
can't be found [1].
I'd say GCC 4.3 does the correct thing but how then was GCC 4.2 able to
compile the setup? I always assumed that "--with-sysroot" is for the
created compiler and "--with-build-sysroot" for the compiler compiling
the new compiler.
Also I'm doing a build=i686-pc-linux-gnu host=i686-pc-mingw32
target=i686-pc-linux-gnu compilation with also --with-sysroot set and
containing glibc and glibc-devel. That works with GCC 4.2 and GCC 4.3. I
would have assumed that GCC 4.3 also fails because it already fails for
a host=i686-pc-linux-gnu.
> --with-build-sysroot=dir
> Tells GCC to consider dir as the system root (see --with-sysroot)
> while building target libraries, instead of the directory specified
> with --with-sysroot.
So this overwrites --with-sysroot for target libraries. What is
--with-sysroot then left to be used for? target binaries? Other things?
> This option is only useful when you are already
> using --with-sysroot. You can use --with-build-sysroot when you are
> configuring with --prefix set to a directory that is different from
> the one in which you are installing GCC and your target libraries.
So assumed I have:
--prefix=/home/me/gcc-tmp
--with-sysroot=/home/me/gcc-tmp/sysroot
But will finally install it into /home/me/gcc. What do I have to set
--with-build-sysroot to? What for? The sysroot will be found relative to
the GCC binaries because it is a subdirectory of the prefix.
> This option affects the system root for the compiler used to build
> target libraries (which runs on the build system); it does not affect
> the compiler which is used to build GCC itself.
And --with-sysroot is used for both? Then for my setup (having sys-root
as a subdir of prefix) makes --with-build-sysroot superfluous?
Where then makes --with-build-sysroot sense? Assumed I do:
--prefix=/home/me/gcc-tmp
--with-sysroot=/home/me/sysroot
Won't it be found absolutely when moving gcc to /home/me/gcc? Or do I
still have to set build-sysroot to /home/me/sysroot?
thanks
Marco
[1] http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30832
