Initial revision

1 files changed, 90 insertions, 0 deletions

diff --git a/README b/README
new file mode 100644
index 0000000..159c1b7
--- /dev/null
+++ b/README
@@ -0,0 +1,90 @@
+Creating a multilib toolchain for Slackware, from scratch
+=========================================================
+
+When you want to build a native multilib toolchain for Slackware64 (glibc,
+gcc and binutils), there are some problems to overcome.
+
+* binutils
+  This is an easy one: just add "--enable-multilib" to the configure command
+  when building the package. In Slackware64, this has already been done
+  for you, so no further action is required.
+
+* glibc
+  This requires a multilib gcc compiler. Also, the SlackBuild needs
+  several edits. The glibc.SlackBuild in Slackware64 will only build the
+  64bit stuff, so we need some explicit additions to compile and package
+  the 32bit components as well. Fred Emmott of Slamd64 has done the heavy
+  lifting to make this happen. However, while Slamd64 has split glibc into
+  a 64bit and a 'compat32' package, I decided to build one big package with
+  the full multilib support included, just like the binutils already have.
+
+* gcc
+  This one is the hardest to crack. The two big issues are (1) you need a
+  multilib-capable gcc compiler to build a multilib gcc compiler suite and
+  (2) you need gnat to build gcc-gnat (the ADA compiler). You can of course
+  "borrow" a set of multilib-capable compiler packages (from Slamd64 for
+  instance) but it is cooler to work only with Slackware64.
+
+
+Detailed compilation steps
+==========================
+
+* Build a barebones, statically compiled gcc only. This is possible
+using the default gcc of Slackware64. I changed the gcc build script to a
+"gcc-static.SlackBuild", this is the script you should run.
+
+* Run "upgradepkg" to upgrade 'gcc' to the new static gcc compiler package
+(keep the remaining gcc-* packages installed!).
+
+* Run ". /etc/profile" to reset your environment. I found out that it
+never hurts to do this from time to time because of all the libraries that
+are changing.
+
+* Build a "bootstrap" version of a multilib glibc. Since only a part of
+the gcc compiler suite is available, some patches need to made to glibc so
+that it compiles successfully. We need this so that we can build a shared
+multilib-capable gcc later. I modified the glibc build script and called
+that "glibc-multilib.SlackBuild". The "bootstrap" packagebuild should be
+run as "./glibc-multilib.SlackBuild --bootstrap".
+
+* Upgrade your glibc-* packages to the new multilib versions of the packages.
+
+* Use this temporary gcc/glibc bootstrap toolchain to build a shared,
+multilib set of packages for the "c,c++,ada" languages. The pre-existing
+gnat compiler will be used by the static gcc to recompile gnat for
+multilib. I re-wrote the gcc.SlackBuild a bit so that I can specify
+more easily what languages I want to build. The updated script is
+called gcc-multilib.Slackuild. Run it as follows: "LANGS='c,c++,ada'
+./gcc-multilib.SlackBuild"
+
+* Remove _all_ gcc-* packages and install the new set of 'gcc' 'gcc-g++'
+and 'gcc-gnat' packages
+
+* Rebuild the glibc packages, this time without the "--bootstrap" parameter
+to "./glibc-multilib.SlackBuild". This is our final set of multilib-capable
+glibc packages.
+
+* Build the complete set of multilib gcc compiler packages:
+"./gcc-multilib.SlackBuild" and run "upgradepkg --reinstall --install-new
+gcc-*.txz" on the new packages.
+
+Done!
+
+
+NOTE
+====
+
+When building a multilib gcc/glibc from scratch on Slackware64, and the
+installed compiler is still built with '--disable-multilib' you need to edit:
+  /usr/lib64/gcc/x86_64-slackware-linux/4.3.3/specs
+and change the lines:
+  *multilib:
+  . !m64 !m32;.:../lib64 m64 !m32;32:../lib !m64 m32;
+to:
+  *multilib:
+  . !m64 !m32;.:../lib64 m64 !m32;../lib !m64 m32;
+or else you will get errors like:
+  checking for suffix of object files... configure: error: cannot compute suffix of object files: cannot compile
+
+=============================================================================
+Eric Hameleers <alien@slackware.com> 25-jun-2009