Document use of CC and CFLAGS in more detail (bug 20980, bug 21234).

There are some bug reports from people setting CFLAGS not including a
-O option and then being confused when the build fails.  This patch
addresses this by documenting the proper use of CC and CFLAGS in more
detail - saying what options should go where and specifying the
requirement to compile with optimization.

The previous text incorrectly used @var markup with CC and CFLAGS.
The correct markup for environment variables is @env, but it's also
the case that passing such variables explicitly on the configure
command line is preferred to passing them in the environment, so this
patch changes the documentation to describe passing them on the
command line (and uses @code).

In many cases putting options in the wrong place may in fact work, but
I believe what I've specified is the correct rule for which options to
put where.

	[BZ #20980]
	[BZ #21234]
	* manual/install.texi (Configuring and compiling): Describe
	passing CC and CFLAGS on configure command line, not as
	environment variables.  Use @code markup on those variables.
	Specify what options go in CC and what go in CFLAGS.  Note the
	requirement to compile with optimization.
	* INSTALL: Regenerated.

1 files changed, 14 insertions, 5 deletions

diff --git a/INSTALL b/INSTALL
index 64dec34..052b1b6 100644
--- a/INSTALL
+++ b/INSTALL
@@ -36,9 +36,18 @@ normal setting to install as the standard system library is
 '--prefix=/usr' for GNU/Linux systems and '--prefix=' (an empty prefix)
 for GNU/Hurd systems.
 
-   It may also be useful to set the CC and CFLAGS variables in the
-environment when running 'configure'.  CC selects the C compiler that
-will be used, and CFLAGS sets optimization options for the compiler.
+   It may also be useful to pass 'CC=COMPILER' and 'CFLAGS=FLAGS'
+arguments to 'configure'.  'CC' selects the C compiler that will be
+used, and 'CFLAGS' sets optimization options for the compiler.  Any
+compiler options required for all compilations, such as options
+selecting an ABI or a processor for which to generate code, should be
+included in 'CC'.  Options that may be overridden by the GNU C Library
+build system for particular files, such as for optimization and
+debugging, should go in 'CFLAGS'.  The default value of 'CFLAGS' is '-g
+-O2', and the GNU C Library cannot be compiled without optimization, so
+if 'CFLAGS' is specified it must enable optimization.  For example:
+
+     $ ../glibc-VERSION/configure CC="gcc -m32" CFLAGS="-O3"
 
    The following list describes all of the available options for
 'configure':
@@ -210,7 +219,7 @@ will be used, and CFLAGS sets optimization options for the compiler.
      but you want to compile a library for 586es, give
      '--host=i586-pc-linux-gnu' or just '--host=i586-linux' and add the
      appropriate compiler flags ('-mcpu=i586' will do the trick) to
-     CFLAGS.
+     'CC'.
 
      If you specify just '--build', 'configure' will get confused.
 
@@ -304,7 +313,7 @@ makefiles.
 setting a few variables in 'configparms'.  Set 'CC' to the
 cross-compiler for the target you configured the library for; it is
 important to use this same 'CC' value when running 'configure', like
-this: 'CC=TARGET-gcc configure TARGET'.  Set 'BUILD_CC' to the compiler
+this: 'configure TARGET CC=TARGET-gcc'.  Set 'BUILD_CC' to the compiler
 to use for programs run on the build system as part of compiling the
 library.  You may need to set 'AR' to cross-compiling versions of 'ar'
 if the native tools are not configured to work with object files for the