Update GCC to 4.9.2

Update the GCC compiler to the 4.9.2 version.  It turns out that a C++
compiler is required to build the latest GCC releases, so build one in
stages 1 and 2 as well.

The updated list of GCC configuration options that either don't work in
a cross compiler or are not needed in a temporary compiler, were based
on the latest instructions from Linux From Scratch.

The inclusion of /lib64 in the lib path for the stage 1 linker is an
attempt to turn things more robust rather than to just symlink in /lib
stuff that ends up installed in /lib64 (as it is already being done for
libgcc_s.so).  Ideally, we should configure every chunk to install to
/lib, however GCC seems to not honour the `--with-libdir` configuration
flag.

With this version of GCC, it looks like a sysroot needs to be given at
configure time so that `--with-native-system-header-dir` does what it
claims to do.  Unfortunately, this has the side effect of making GCC not
passing to the linker the linker sysroot flag: `-Wl,--sysroot=$SYSROOT`.
The workaround is to modify LDFLAGS to give a sysroot directly to GCC,
`--sysroot=$SYSROOT`, which will then be further passed down to the
linker.

As the newest version of GCC finds more warnings than the previous one,
`-Werror` was disabled for the coreutils, GDB and Syslinux projects.
Syslinux's Makefile had to be patched, as it is not possible to disable
`-Werror` for all targets through the NO_WERROR variable.

The hack to handle libgcc_eh being required during eglibc's build was
removed, as it doesn't seem to be the case anymore.

1 files changed, 12 insertions, 6 deletions

diff --git a/strata/build-essential/stage1-binutils.morph b/strata/build-essential/stage1-binutils.morph
index b6670d5c..69a79d14 100644
--- a/strata/build-essential/stage1-binutils.morph
+++ b/strata/build-essential/stage1-binutils.morph
@@ -3,15 +3,21 @@ kind: chunk
 build-system: autotools
 
 configure-commands:
-# We set the sysroot location dynamically at runtime by passing -B to GCC,
-# so we configure with sysroot=/. Setting the lib path is vital to avoid
-# the tools we build linking to the libraries on the host system; the '='
-# makes the path we give relative to the sysroot, which we can then set
-# at runtime by passing -Wl,--sysroot to GCC.
+# We set the sysroot location dynamically at runtime by passing
+# `--sysroot` to GCC, so we need to build a linker with sysroot support.
+# We set it to a non-existent directory as a safety net to avoid looking
+# at the host dirs in case we forget to set the sysroot.  Setting the
+# lib path is vital to avoid the tools we build linking to the libraries
+# on the host system; the '=' makes the path we give relative to the
+# sysroot, which we can then set at runtime by passing -Wl,--sysroot to
+# GCC.  Although nothing should be installed on /lib64, we configure the
+# linker to look at that directory as well to make things more robust
+# (currently GCC installs libraries to this directory at least on
+# x86_64).
 
 - |
   ./configure --prefix="$PREFIX" --disable-nls --disable-werror \
     --build=$(sh config.guess) \
     --host=$(sh config.guess) \
     --target=$TARGET_STAGE1 \
-    --with-sysroot="/" --with-lib-path="=$PREFIX/lib"
+    --with-sysroot=/nonexistentdir --with-lib-path="=$PREFIX/lib:=$PREFIX/lib64"