Add an instruction about stacktrace on x86-64 in INSTALL file. Basically, this

note was copied from google-perftools's notice (google-perftools/INSTALL).  I
modified the notice because the situation around stacktracer is a bit different
between glog and perftools.  Perftool's tcmalloc hooks malloc and its
stacktracer must not call malloc.  In glog, stacktracer with malloc can be an
issue only when users use InstallFailureSignalHandler() and a signal is raised
inside malloc.


git-svn-id: https://google-glog.googlecode.com/svn/trunk@19 eb4d4688-79bd-11dd-afb4-1d65580434c0

INSTALL

-Copyright 1994, 1995, 1996, 1999, 2000, 2001, 2002 Free Software
-Foundation, Inc.
+Installation Instructions
+*************************
 
-   This file is free documentation; the Free Software Foundation gives
+Copyright (C) 1994, 1995, 1996, 1999, 2000, 2001, 2002, 2004, 2005,
+2006, 2007 Free Software Foundation, Inc.
+
+This file is free documentation; the Free Software Foundation gives
 unlimited permission to copy, distribute and modify it.
 
+Glog-Specific Install Notes
+================================
+
+*** NOTE FOR 64-BIT LINUX SYSTEMS
+
+The glibc built-in stack-unwinder on 64-bit systems has some problems
+with the glog libraries.  (In particular, if you are using
+InstallFailureSignalHandler(), the signal may be raised in the middle
+of malloc, holding some malloc-related locks when they invoke the
+stack unwinder.  The built-in stack unwinder may call malloc
+recursively, which may require the thread to acquire a lock it already
+holds: deadlock.)
+
+For that reason, if you use a 64-bit system and you need
+InstallFailureSignalHandler(), we strongly recommend you install
+libunwind before trying to configure or install google glog.
+libunwind can be found at
+
+   http://download.savannah.nongnu.org/releases/libunwind/libunwind-snap-070410.tar.gz
+
+Even if you already have libunwind installed, you will probably still
+need to install from the snapshot to get the latest version.
+
+CAUTION: if you install libunwind from the URL above, be aware that
+you may have trouble if you try to statically link your binary with
+glog: that is, if you link with 'gcc -static -lgcc_eh ...'.  This
+is because both libunwind and libgcc implement the same C++ exception
+handling APIs, but they implement them differently on some platforms.
+This is not likely to be a problem on ia64, but may be on x86-64.
+
+Also, if you link binaries statically, make sure that you add
+-Wl,--eh-frame-hdr to your linker options. This is required so that
+libunwind can find the information generated by the compiler required
+for stack unwinding.
+
+Using -static is rare, though, so unless you know this will affect you
+it probably won't.
+
+If you cannot or do not wish to install libunwind, you can still try
+to use two kinds of stack-unwinder: 1. glibc built-in stack-unwinder
+and 2. frame pointer based stack-unwinder.
+
+1. As we already mentioned, glibc's unwinder has a deadlock issue.
+However, if you don't use InstallFailureSignalHandler() or you don't
+worry about the rare possibilities of deadlocks, you can use this
+stack-unwinder.  If you specify no options and libunwind isn't
+detected on your system, the configure script chooses this unwinder by
+default.
+
+2. The frame pointer based stack unwinder requires that your
+application, the glog library, and system libraries like libc, all be
+compiled with a frame pointer.  This is *not* the default for x86-64.
+
+If you are on x86-64 system, know that you have a set of system
+libraries with frame-pointers enabled, and compile all your
+applications with -fno-omit-frame-pointer, then you can enable the
+frame pointer based stack unwinder by passing the
+--enable-frame-pointers flag to configure.
+
 
 Basic Installation
 ==================
 
-   These are generic installation instructions.
+Briefly, the shell commands `./configure; make; make install' should
+configure, build, and install this package.  The following
+more-detailed instructions are generic; see the `README' file for
+instructions specific to this package.
 
    The `configure' shell script attempts to guess correct values for
 various system-dependent variables used during compilation.  It uses
@@ -21,9 +86,9 @@ debugging `configure').
 
    It can also use an optional file (typically called `config.cache'
 and enabled with `--cache-file=config.cache' or simply `-C') that saves
-the results of its tests to speed up reconfiguring.  (Caching is
+the results of its tests to speed up reconfiguring.  Caching is
 disabled by default to prevent problems with accidental use of stale
-cache files.)
+cache files.
 
    If you need to do unusual things to compile the package, please try
 to figure out how `configure' could check whether to do them, and mail
@@ -33,20 +98,17 @@ some point `config.cache' contains results you don't want to keep, you
 may remove or edit it.
 
    The file `configure.ac' (or `configure.in') is used to create
-`configure' by a program called `autoconf'.  You only need
-`configure.ac' if you want to change it or regenerate `configure' using
-a newer version of `autoconf'.
+`configure' by a program called `autoconf'.  You need `configure.ac' if
+you want to change it or regenerate `configure' using a newer version
+of `autoconf'.
 
 The simplest way to compile this package is:
 
   1. `cd' to the directory containing the package's source code and type
-     `./configure' to configure the package for your system.  If you're
-     using `csh' on an old version of System V, you might need to type
-     `sh ./configure' instead to prevent `csh' from trying to execute
-     `configure' itself.
+     `./configure' to configure the package for your system.
 
-     Running `configure' takes awhile.  While running, it prints some
-     messages telling which features it is checking for.
+     Running `configure' might take a while.  While running, it prints
+     some messages telling which features it is checking for.
 
   2. Type `make' to compile the package.
 
@@ -65,54 +127,55 @@ The simplest way to compile this package is:
      all sorts of other programs in order to regenerate files that came
      with the distribution.
 
+  6. Often, you can also type `make uninstall' to remove the installed
+     files again.
+
 Compilers and Options
 =====================
 
-   Some systems require unusual options for compilation or linking that
-the `configure' script does not know about.  Run `./configure --help'
-for details on some of the pertinent environment variables.
+Some systems require unusual options for compilation or linking that the
+`configure' script does not know about.  Run `./configure --help' for
+details on some of the pertinent environment variables.
 
    You can give `configure' initial values for configuration parameters
 by setting variables in the command line or in the environment.  Here
 is an example:
 
-     ./configure CC=c89 CFLAGS=-O2 LIBS=-lposix
+     ./configure CC=c99 CFLAGS=-g LIBS=-lposix
 
    *Note Defining Variables::, for more details.
 
 Compiling For Multiple Architectures
 ====================================
 
-   You can compile the package for more than one kind of computer at the
+You can compile the package for more than one kind of computer at the
 same time, by placing the object files for each architecture in their
-own directory.  To do this, you must use a version of `make' that
-supports the `VPATH' variable, such as GNU `make'.  `cd' to the
+own directory.  To do this, you can use GNU `make'.  `cd' to the
 directory where you want the object files and executables to go and run
 the `configure' script.  `configure' automatically checks for the
 source code in the directory that `configure' is in and in `..'.
 
-   If you have to use a `make' that does not support the `VPATH'
-variable, you have to compile the package for one architecture at a
-time in the source code directory.  After you have installed the
-package for one architecture, use `make distclean' before reconfiguring
-for another architecture.
+   With a non-GNU `make', it is safer to compile the package for one
+architecture at a time in the source code directory.  After you have
+installed the package for one architecture, use `make distclean' before
+reconfiguring for another architecture.
 
 Installation Names
 ==================
 
-   By default, `make install' will install the package's files in
-`/usr/local/bin', `/usr/local/man', etc.  You can specify an
-installation prefix other than `/usr/local' by giving `configure' the
-option `--prefix=PATH'.
+By default, `make install' installs the package's commands under
+`/usr/local/bin', include files under `/usr/local/include', etc.  You
+can specify an installation prefix other than `/usr/local' by giving
+`configure' the option `--prefix=PREFIX'.
 
    You can specify separate installation prefixes for
 architecture-specific files and architecture-independent files.  If you
-give `configure' the option `--exec-prefix=PATH', the package will use
-PATH as the prefix for installing programs and libraries.
-Documentation and other data files will still use the regular prefix.
+pass the option `--exec-prefix=PREFIX' to `configure', the package uses
+PREFIX as the prefix for installing programs and libraries.
+Documentation and other data files still use the regular prefix.
 
    In addition, if you use an unusual directory layout you can give
-options like `--bindir=PATH' to specify different values for particular
+options like `--bindir=DIR' to specify different values for particular
 kinds of files.  Run `configure --help' for a list of the directories
 you can set and what kinds of files go in them.
 
@@ -123,7 +186,7 @@ option `--program-prefix=PREFIX' or `--program-suffix=SUFFIX'.
 Optional Features
 =================
 
-   Some packages pay attention to `--enable-FEATURE' options to
+Some packages pay attention to `--enable-FEATURE' options to
 `configure', where FEATURE indicates an optional part of the package.
 They may also pay attention to `--with-PACKAGE' options, where PACKAGE
 is something like `gnu-as' or `x' (for the X Window System).  The
@@ -138,11 +201,11 @@ you can use the `configure' options `--x-includes=DIR' and
 Specifying the System Type
 ==========================
 
-   There may be some features `configure' cannot figure out
-automatically, but needs to determine by the type of machine the package
-will run on.  Usually, assuming the package is built to be run on the
-_same_ architectures, `configure' can figure that out, but if it prints
-a message saying it cannot guess the machine type, give it the
+There may be some features `configure' cannot figure out automatically,
+but needs to determine by the type of machine the package will run on.
+Usually, assuming the package is built to be run on the _same_
+architectures, `configure' can figure that out, but if it prints a
+message saying it cannot guess the machine type, give it the
 `--build=TYPE' option.  TYPE can either be a short name for the system
 type, such as `sun4', or a canonical name which has the form:
 
@@ -157,7 +220,7 @@ where SYSTEM can have one of these forms:
 need to know the machine type.
 
    If you are _building_ compiler tools for cross-compiling, you should
-use the `--target=TYPE' option to select the type of system they will
+use the option `--target=TYPE' to select the type of system they will
 produce code for.
 
    If you want to _use_ a cross compiler, that generates code for a
@@ -168,9 +231,9 @@ eventually be run) with `--host=TYPE'.
 Sharing Defaults
 ================
 
-   If you want to set default values for `configure' scripts to share,
-you can create a site shell script called `config.site' that gives
-default values for variables like `CC', `cache_file', and `prefix'.
+If you want to set default values for `configure' scripts to share, you
+can create a site shell script called `config.site' that gives default
+values for variables like `CC', `cache_file', and `prefix'.
 `configure' looks for `PREFIX/share/config.site' if it exists, then
 `PREFIX/etc/config.site' if it exists.  Or, you can set the
 `CONFIG_SITE' environment variable to the location of the site script.
@@ -179,7 +242,7 @@ A warning: not all `configure' scripts look for a site script.
 Defining Variables
 ==================
 
-   Variables not defined in a site shell script can be set in the
+Variables not defined in a site shell script can be set in the
 environment passed to `configure'.  However, some packages may run
 configure again during the build, and the customized values of these
 variables may be lost.  In order to avoid this problem, you should set
@@ -187,14 +250,18 @@ them in the `configure' command line, using `VAR=value'.  For example:
 
      ./configure CC=/usr/local2/bin/gcc
 
-will cause the specified gcc to be used as the C compiler (unless it is
+causes the specified `gcc' to be used as the C compiler (unless it is
 overridden in the site shell script).
 
+Unfortunately, this technique does not work for `CONFIG_SHELL' due to
+an Autoconf bug.  Until the bug is fixed you can use this workaround:
+
+     CONFIG_SHELL=/bin/bash /bin/bash ./configure CONFIG_SHELL=/bin/bash
+
 `configure' Invocation
 ======================
 
-   `configure' recognizes the following options to control how it
-operates.
+`configure' recognizes the following options to control how it operates.
 
 `--help'
 `-h'