TITLE: Multiple GCC Installations
LFS VERSION: All
AUTHOR: Eric Crahen <crahen@cse.buffalo.edu>
SYNOPSIS:
This is a set of instructions for people interested in installing
and using several versions of gcc on thier system. The compiler's
public interfaces are renamed to include version numbers (e.g.
gcc-2.95.3), version specific dependancies, such as includes and
shared libraries are storeed in different locations and evironment
variables replace can be used to select a compiler (rather than
global names such as /usr/bin or /lib/cpp)
OBTAIN THE SOURCE:
First, you need to obtain the version of gcc you wish to compile
and install along with any patches that come with it. The example,
will demonstrate how to install two common versions of the compiler.
EGCS-1.1.2:
ftp://sourceware.cygnus.com/pub/gcc/old-releases/egcs/
http://gcc.gnu.org/install/glibc-2.2.patch
GCC-2.95.3:
ftp://ftp.gnu.org/pub/gnu/gcc/
COMPILE THE SOURCE & INSTALL:
Next, the source needs to be configured. This is done in the usual
way, the important configuration options are the following:
--enable-version-specific-runtime-libs
Keeps the version specific runtime libraries in a compiler specific
directory rather than placing them right in ${libdir}. You can read
more about this in the gcc documentation (install/CONFIGURE).
--program-transform-name
Transforms the binary file names when they are installed using a
sed regular expression. This option will be used to append the version
number as a suffix to the binary names. You can read more about this
by running configure (./configure --help).
The following two examples demonstrate a typical use of these options.
ECGS-1.1.2:
sed -e s/gcc-2.95.2/egcs-1.1.2/ glibc-2.2.patch | patch -p0; \
mkdir egcs-build && cd egcs-build && \
../egcs-1.1.2/configure --prefix=/usr \
--enable-languages --enable-languages=c,c++ \
--enable-threads=posix \
--enable-version-specific-runtime-libs \
--program-transform-name="s/\\\\(.*\\\\)/\\\\1-2.91.66/" && \
make bootstrap && make install && \
ln -s /usr/bin/gcc-2.91.66 cc-2.91.66
GCC-2.95.3:
bzip2 -dc gcc-2.95.3-2.patch.bz2 | patch -Np1; &&
mkdir ../gcc-build && cd ../gcc-build &&
../gcc-2.95.3/configure --prefix=/usr \
--enable-languages --enable-languages=c,c++ \
--enable-threads=posix \
--enable-version-specific-runtime-libs \
--program-transform-name="s/\\\\(.*\\\\)/\\\\1-2.95.3/" && \
make bootstrap && make install \
ln -s /usr/bin/gcc-2.95.3 cc-2.95.3
CONFIGURE YOUR ENVIRONMENT:
To configure the environment, several variables need to be set. One
is the PATH, it should include the path to wherever the binaries
have been installed. If the binaries are installed in a location like
/usr/bin then that location needs to be in your PATH. The two
variables that are used to select the compiler also need to be set.
These are CC and CXX and they should point to cc-version and
c++-version respectively.
For example, if you want gcc-2.95.3 to be the default, the following
commands can be used.
CC=cc-2.95.3 && \
CXX=c++-2.95.3 && \
export CC CXX
These commands can be placed in an rc file that will be executed when
your shell is spawned. For example, /etc/profile or ~/.bashrc.
GNU tools, such as autoconf or make can detect your compiler by
looking at these variables. In most cases, there is nothing extra that
will need to be done to use these variables to select a compiler.
However, there are exceptions and there are notes at the end of the
document about those exceptions.
SELECTING A DIFFERENT COMPILER:
Selecting a different compiler simply becomes a matter of chaning
the value of the CC and CXX variables.
For instance, to switch from the currently selected compiler to
egcs the following commands can be used
CC=cc-2.91.66 && \
CXX=c++-2.91.66 && \
export CC CXX
NOTES:
1.) The '--program-transform-name' option doesn't do anything!?
This is can be frustrating because you won't find the error until
you have compiled and installed the source and notices the binary
names have not changed. The reason is almost certainly because the
regular expression has not been escaped properly. Test your expression
with sed and quadruple the number of \'s used to escape it.
Why? Well, suppose you want to add a suffix to a word. The following
sed expression does this. You need to escape special characters for
sed.
echo name | sed -e "s/\(.*\)/\1-suffix/"
If you want to get that expression into a Makefile as a string that
the Makefile will eventually execute, you have to escape that
expression.
s/\\(.*\\)/\\1-suffix/
So, to get the string show above from a shell prompt into any program
you have to escape it again for the shell. So you end up with,
s/\\\\(.*\\\\)/\\\\1-suffix/
And the configure option becomes,
--program-transform-name="s/\\\\(.*\\\\)/\\\\1-suffix/"
2.) Things compile, but they are broken!?
You may be are mixing compiler versions. Make sure your CC and CXX
variables are both using the binaries with the same suffix.
DON'T (suffixes are mismatched)
CC=cc-2.91.66
CXX=cc-2.95.3
DO (suffixes are matched)
CC=cc-2.95.3
CXX=cc-2.95.3
3.) glibc doesn't compile now!?
Because glibc assumes your c preprocessor is named cpp and is
located in /lib/cpp you may have difficulty compiling glibc.
To make glibc choose the correct preprocessor binary the following
path can be applied to the source for glibc-2.2.4 so the correct
compiler will be chosen for a linux system.
cat > glibc-2.2.4-cpp0.patch << "EOF"
2002-20 Eric Crahen <crahen@cse.buffalo.edu>
Make sunrpc compile selecting the version specific
c preprocessor reported by whatever gcc CC points at.
--- glibc-2.2.4-vanilla/sunrpc/rpc_main.c Thu Apr 12 17:02:07 2001
+++ glibc-2.2.4/sunrpc/rpc_main.c Sun Jan 20 20:35:51 2002
@@ -1323,7 +1323,7 @@
return 0;
{
size_t len = strlen (argv[i]);
- pathbuf = malloc (len + 5);
+ pathbuf = malloc (len + 6);
if (pathbuf == NULL)
{
perror (cmdname);
@@ -1331,7 +1331,7 @@
}
stpcpy (stpcpy (pathbuf,
argv[i]),
- "/cpp");
+ "/cpp0");
CPP = pathbuf;
cppDefined = 1;
goto nextarg;
--- glibc-2.2.4-vanilla/sunrpc/Makefile Mon Jul 23 13:55:17 2001
+++ glibc-2.2.4/sunrpc/Makefile Sun Jan 20 20:31:26 2002
@@ -126,8 +126,8 @@
$(+link)
# Tell rpcgen where to find the C preprocessor.
-rpcgen-cmd = $(built-program-cmd) -Y `$(CC) -print-file-name=cpp | \
- sed 's|/cpp$$||'`
+rpcgen-cmd = $(built-program-cmd) -Y `$(CC) -print-file-name=cpp0 | \
+ sed 's|/cpp0$$||'`
# Install the rpc data base file.
$(inst_sysconfdir)/rpc: etc.rpc $(+force)
EOF
4.) The kernel doesn't compile now!?
In the kernel, 'gcc' is hard coded gcc into the Makefile. One way to
overcome this is to use sed.
sed -e s/gcc/$CC/ Makefile | make -f - dep && \
sed -e s/gcc/$CC/ Makefile | make -f - modules && \
sed -e s/gcc/$CC/ Makefile | make -f - modules_install && \
sed -e s/gcc/$CC/ Makefile | make -f - bzImage
5.) XFree86 doesn't compile now / An X11 program doesn't compile !?
Compiling this is tricky when you don't have a common name for your
compiler. XFree86 is setup using imake which keeps a database of
dependancies. Typically, imake assumes certain compilers are installed
and looks for them using the common names and locations /lib/cpp and
/usr/bin/gcc. These assumptions can be changed by updating the correct
configuration file in the xc/config/cf directory.
For a linux system, you can update that file with the following
commands.
cp config/cf/linux.cf config/cf/linux.cf.orig && \
IMAKECPP=`$CC -print-file-name=cpp0` && export IMAKECPP && \
sed -e "s/gcc/$CC/;s/.++/$CXX/;" config/cf/linux.cf.orig > \
/tmp/linux.cf && \
sed -e s,\\\/lib\\\/cpp,`echo $IMAKECPP | sed 's|/|\\\\/|g'`, \
/tmp/linux.cf | sed '/# define CppCmd/a \
# ifndef RawCppCmd \
# define RawCppCmd CppCmd -A- \
# endif \
' > config/cf/linux.cf && \
rm -f /tmp/linux.cf
The top part of this command allows both make and imake to
use the compiler names you specify in CC and CXX.
The lower portion,
sed '/# define CppCmd/a\
# ifndef RawCppCmd \
# define RawCppCmd CppCmd -A- \
# endif \
'
Tells the preprocessor to use the correct undef option.
By default, it will attempt to used -undef, which may not
work with your compiler depending on the version and how you've
compiled it. The wrong undef option will cause you to end up with
a bunch of blank man pages.
Some X11 program use imake, so you might want to place those
first few lines (those that define IMAKECPP) in an rc file.
6.) Another program doesn't compile now!?
I've shown two of the trickier programs to compile. The vast majority
of source not configurable using autoconf will set a variable for the
compiler in a Makefile. To overcome that, all that needs to be done is
to override that variable.
You can tell make to look at your environment using 'make -e'.
OR
You can set some vairables 'using make VAR=val'.
7.) My cross compiler isn't renamed!?
This is because of how gcc built. You can change the
program_transform_name variable in the Makefile, but you can't change
the program_transform_cross_name variable. To update that you'd need
to edit the Makefile template in the gcc subdirectory of your gcc
source tree. Below is a patch for this that will patch the two
compilers used as examples throughout the document.
cat > gcc-cross-rename.patch << "EOF"
2002-21 Eric Crahen <crahen@cse.buffalo.edu>
* Rename the cross compiler binaries to have a version
suffix for GCC-2.95.3 and EGCS-1.1.2
--- gcc-2.95.3/gcc/Makefile.in.orig Mon Jan 21 09:19:33 2002
+++ gcc-2.95.3/gcc/Makefile.in Mon Jan 21 09:20:47 2002
@@ -2569,7 +2569,7 @@
$(INSTALL_PROGRAM) xgcc$(exeext) $(bindir)/$(GCC_INSTALL_NAME)$(exeext); \
rm -f $(bindir)/$(target_alias)-gcc-1$(exeext); \
$(LN) $(bindir)/$(GCC_INSTALL_NAME)$(exeext) $(bindir)/$(target_alias)-gcc-1$(exeext); \
- mv $(bindir)/$(target_alias)-gcc-1$(exeext) $(bindir)/$(target_alias)-gcc$(exeext); \
+ mv $(bindir)/$(target_alias)-gcc-1$(exeext) $(bindir)/$(target_alias)-gcc-2.95.3$(exeext); \
fi
# Install the info files.
--- egcs-1.1.2/gcc/Makefile.in.orig Mon Jan 21 08:41:22 2002
+++ egcs-1.1.2/gcc/Makefile.in Mon Jan 21 08:57:45 2002
@@ -2403,7 +2403,7 @@
$(INSTALL_PROGRAM) xgcc$(exeext) $(bindir)/$(GCC_INSTALL_NAME)$(exeext); \
rm -f $(bindir)/$(target_alias)-gcc-1$(exeext); \
$(LN) $(bindir)/$(GCC_INSTALL_NAME)$(exeext) $(bindir)/$(target_alias)-gcc-1$(exeext); \
- mv $(bindir)/$(target_alias)-gcc-1$(exeext) $(bindir)/$(target_alias)-gcc$(exeext); \
+ mv $(bindir)/$(target_alias)-gcc-1$(exeext) $(bindir)/$(target_alias)-gcc-2.91.66$(exeext); \
fi
# Install the info files.
EOF