diff --git a/doc/Makefile.am b/doc/Makefile.am
index db34ba9..fb84652 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -1,95 +1,95 @@
 # Makefile.am for libgpg-error documentation
 # Copyright (C) 2014 g10 Code GmbH
 #
 # This file is part of libgpg-error.
 #
 # libgpg-error is free software; you can redistribute it and/or modify
 # it under the terms of the GNU Lesser General Public License as
 # published by the Free Software Foundation; either version 2.1 of the
 # License, or (at your option) any later version.
 #
 # libgpg-error is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU Lesser General Public License for more details.
 #
 # You should have received a copy of the GNU Lesser General Public
 # License along with this program; if not, see <https://www.gnu.org/licenses/>.
 
 
 EXTRA_DIST = HACKING errorref.txt
 
 bin_PROGRAMS = yat2m
 yat2m_SOURCES = yat2m.c
 yat2m_CFLAGS= -DPACKAGE_VERSION="\"$(PACKAGE_VERSION)\""
 
 DISTCLEANFILES = gpgrt.cps yat2m-stamp.tmp yat2m-stamp $(myman_pages)
 CLEANFILES = errorref.txt.x
 
 info_TEXINFOS = gpgrt.texi
 gpgrt_TEXINFOS = lgpl.texi gpl.texi
 
 YAT2M_OPTIONS = -I $(srcdir) \
 	--release "Libgpg-error @PACKAGE_VERSION@" --source "GnuPG"
 
 myman_sources = gpgrt.texi
 if INSTALL_GPG_ERROR_CONFIG
-myman_pages   = gpg-error-config.1
+myman_pages   = gpg-error-config.1 gpgrt-config.1
 else
-myman_pages   =
+myman_pages   = gpgrt-config.1
 endif
 
 man_MANS = $(myman_pages)
 
 if CROSS_COMPILING
 YAT2M_CMD = ./yat2m-for-build$(EXEEXT_FOR_BUILD)
 YAT2M_DEP = yat2m-for-build$(EXEEXT_FOR_BUILD)
 CLEANFILES += yat2m-for-build$(EXEEXT_FOR_BUILD)
 
 yat2m-for-build$(EXEEXT_FOR_BUILD): yat2m.c
 	$(CC_FOR_BUILD) $(CFLAGS_FOR_BUILD) $(LDFLAGS_FOR_BUILD) \
 	$(CPPFLAGS_FOR_BUILD) -o $@ $(srcdir)/yat2m.c
 else
 YAT2M_CMD = ./yat2m$(EXEEXT)
 YAT2M_DEP = yat2m$(EXEEXT)
 endif
 
 yat2m-stamp: $(myman_sources) $(srcdir)/version.texi
 	@rm -f yat2m-stamp.tmp
 	@touch yat2m-stamp.tmp
 	for file in $(myman_sources) ; do \
               $(YAT2M_CMD) $(YAT2M_OPTIONS) --store \
 	          `test -f '$$file' || echo '$(srcdir)/'`$$file ; done
 	@mv -f yat2m-stamp.tmp $@
 
 yat2m-stamp: $(YAT2M_DEP)
 
 $(myman_pages) : yat2m-stamp
 	@if test -f $@; then :; else \
             trap 'rm -rf yat2m-stamp yat2m-lock' 1 2 13 15; \
                if mkdir yat2m-lock 2>/dev/null; then \
                  rm -f yat2m-stamp; \
                  $(MAKE) $(AM_MAKEFLAGS) yat2m-stamp; \
                  rmdir yat2m-lock; \
                else \
                  while test -d yat2m-lock; do sleep 1; done; \
                  test -f yat2m-stamp; exit $$?; \
                fi; \
              fi
 
 # Make sure that gpgrt.texi is touched if any other texi file has
 # been modified.  This is required so that the version.texi magic
 # updates the release date.
 gpgrt.texi : $(gpgrt_TEXINFOS)
 	touch $(srcdir)/gpgrt.texi
 
 errorref.txt.x : errorref.txt
 	sed '/^##/ d' $(srcdir)/errorref.txt >$@
 	echo "# Installed by $(PACKAGE_NAME) $(PACKAGE_VERSION)" >>$@
 
 install-data-local: errorref.txt.x
 	$(mkinstalldirs) $(DESTDIR)$(pkgdatadir)
 	$(INSTALL_DATA) errorref.txt.x $(DESTDIR)$(pkgdatadir)/errorref.txt
 
 uninstall-local:
 	-@rm $(DESTDIR)$(pkgdatadir)/errorref.txt
diff --git a/doc/gpgrt.texi b/doc/gpgrt.texi
index 2478366..6612600 100644
--- a/doc/gpgrt.texi
+++ b/doc/gpgrt.texi
@@ -1,440 +1,507 @@
 \input texinfo                  @c -*- Texinfo -*-
 @c %**start of header
 @setfilename gpgrt.info
 @include version.texi
 @settitle The Libgpg-error Reference Manual
 @c Unify some of the indices.
 @syncodeindex tp fn
 @syncodeindex pg fn
 @c %**end of header
 @copying
 This manual is for Libgpg-error (version @value{VERSION},
 @value{UPDATED}), which is a library for code used by all GnuPG
 related packages.
 
 @noindent
 Copyright @copyright{} 2014, 2022 g10 Code GmbH
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU General Public License as published by the
 Free Software Foundation; either version 2 of the License, or (at your
 option) any later version. The text of the license can be found in the
 section entitled ``GNU General Public License''.
 @end quotation
 @end copying
 
 @dircategory Libraries
 @direntry
 * libgpg-error: (gpgrt).   Error codes and common code for GnuPG.
 @end direntry
 
 @c A couple of macros with no effect on texinfo
 @c but used by the yat2m processor.
 @macro manpage {a}
 @end macro
 @macro mansect {a}
 @end macro
 @macro manpause
 @end macro
 @macro mancont
 @end macro
 
 @c
 @c Printing stuff taken from gcc.
 @c
 @macro gnupgtabopt{body}
 @code{\body\}
 @end macro
 
 
 @c
 @c Titlepage
 @c
 @setchapternewpage odd
 @titlepage
 @title The Libgpg-error Reference Manual
 @subtitle Version @value{VERSION}
 @subtitle @value{UPDATED}
 @author Werner Koch (@email{wk@@gnupg.org})
 
 @page
 @vskip 0pt plus 1filll
 @insertcopying
 @end titlepage
 
 @ifnothtml
 @summarycontents
 @contents
 @page
 @end ifnothtml
 
 
 @ifnottex
 @node Top
 @top The Libgpg-error Library
 @insertcopying
 @end ifnottex
 
 
 @menu
 * Introduction::                 What is Libgpg-error.
 * Preparation::                  What you should do before using the library.
 * Generalities::                 General library functions and data types.
 * Tools::                        Utility tools
 
 Appendices
 
 * Library Copying::             The GNU Lesser General Public License
                                 says how you can copy and share Libgpg-error.
 * Copying::                     The GNU General Public License says how you
                                 can copy and share some parts of Libgpg-error.
 
 Indices
 
 @c * Figures and Tables::          Index of figures and tables.
 * Concept Index::               Index of concepts and programs.
 * Function and Data Index::     Index of functions, variables and data types.
 
 @end menu
 
 @ifhtml
 @page
 @summarycontents
 @contents
 @end ifhtml
 
 
 @c **********************************************************
 @c *******************  Introduction  ***********************
 @c **********************************************************
 @node Introduction
 @chapter Introduction
 
 Libgpg-error is a library to provide error codes for GnuPG and relates
 software as well as some other general purpose functions.  It is
 planned to eventually rename this library to ``gpgrt'' (for GnuPG
 RunTime).
 
 @menu
 * Getting Started::             How to use this manual.
 * Features::                    A glance at Libgpg-error’s features.
 * Overview::                    Overview about the library.
 @end menu
 
 @node Getting Started
 @section Getting Started
 
 This manual documents the Libgpg-error library application programming
 interface (API).  The goal is to that all functions and data types
 provided by the library are explained.  However, for now this is only
 a stub and not very useful.
 
 
 @node Features
 @section Features
 
 TBD
 
 @node Overview
 @section Overview
 
 @noindent
 The Libgpg-error library is fully thread-safe, where it makes
 sense to be thread-safe.
 
 TBD
 
 @c **********************************************************
 @c *******************  Preparation  ************************
 @c **********************************************************
 @node Preparation
 @chapter Preparation
 
 To use Libgpg-error, you have to perform some changes to your
 sources and the build system.  The necessary changes are small and
 explained in the following sections.  At the end of this chapter, it
 is described how the library is initialized, and how the requirements
 of the library are verified.
 
 @menu
 * Header::                      What header file you need to include.
 * Building sources::            How to build sources using the library.
 * Building sources using Automake::  How to build sources with the help of Automake.
 * Initializing the library::    How to initialize the library.
 * Multi-Threading::             How Libgpg-error can be used in a MT environment.
 @end menu
 
 
 @node Header
 @section Header
 
 All interfaces (data types and functions) of the library are defined
 in the header file @file{gpg-error.h}.  You must include this in all source
 files using the library, either directly or through some other header
 file, like this:
 
 @example
 #include <gpg-error.h>
 @end example
 
 Note well that the header file is platform specific and may only be
 used on the platform for which it has been build.
 
 The name space of Libgpg-error is @code{gpg_*} and @code{gpgrt*}
 for function and type names and @code{GPG_*} and @code{GPGRT_*}
 for other symbols.  In addition the same name prefixes with one
 prepended underscore are reserved for internal use and should never be
 used by an application.
 
 @noindent
 Certain parts of gpg-error.h may be included by defining these macros:
 
 @table @code
 @item GPG_ERR_ENABLE_GETTEXT_MACROS
 Define to provide macros to map the internal gettext API to standard
 names.  This has only an effect on Windows platforms.
 
 @item GPGRT_ENABLE_ES_MACROS
 Define to provide "es_" macros for the estream functions.
 @end table
 
 @node Building sources
 @section Building sources
 
 If you want to compile a source file including the `gpg-error.h' header
 file, you must make sure that the compiler can find it in the
 directory hierarchy.  This is accomplished by adding the path to the
 directory in which the header file is located to the compilers include
 file search path (via the @option{-I} option).
 
 However, the path to the include file is determined at the time the
 source is configured.  To solve this problem, Libgpg-error ships with
 a pkg-config file: gpg-error.pc.
 
 The options that need to be added to the compiler invocation at
 compile time are output by the @option{--cflags} option to
 @command{pkg-config}.  The following example shows how it can be used
 at the command line:
 
 @example
 gcc -c foo.c $(pkg-config --cflags gpg-error)
 @end example
 
 Adding the output of @samp{pkg-config --cflags gpg-error} to the
 compiler’s command line will ensure that the compiler can find the
 Libgpg-error header file.
 
 A similar problem occurs when linking the program with the library.
 Again, the compiler has to find the library files.  For this to work,
 the path to the library files has to be added to the library search
 path (via the @option{-L} option).  For this, the option
 @option{--libs} to @command{pkg-config} can be used.  The example
 shows how to link @file{foo.o} with the Libgpg-error library to a
 program @command{foo}.
 
 @example
 gcc -o foo foo.o $(pkg-config --libs gpg-error)
 @end example
 
 Of course you can also combine both examples to a single command by
 specifying both options to @command{pkg-config}:
 
 @example
 gcc -o foo foo.c $(pkg-config --cflags --libs gpg-error)
 @end example
 
 For GnuPG and its friends, which are usually needed to be built
 earlier in a stage of OS bootstrap, Libgpg-error ships the small
 helper program @command{gpgrt-config}.  This helper program is a sort
 of @command{pkg-config} replacement for limited environment,
 supporting cross compilation, as well as multilib and multi-arch
 installation.  Note that @command{gpgrt-config} is not for general use
 for other programs.  @command{gpgrt-config} requires invocation with
 the option @option{--lib=} so that it locates the appropriate path to
 @file{gpg-error.pc}.
 
 
 @node Building sources using Automake
 @section Building sources using Automake
 
 It is much easier if you use GNU Automake instead of writing your own
 Makefiles.  If you do that, you do not have to worry about finding and
 invoking the @command{pkg-config} or @command{gpgrt-config} script at
 all.  Libgpg-error provides an extension to Automake that does all the
 work for you.  That is offered by @file{gpg-error.m4}.
 
 @c A simple macro for optional variables.
 @macro ovar{varname}
 @r{[}@var{\varname\}@r{]}
 @end macro
 @defmac AM_PATH_GPG_ERROR (@ovar{minimum-version}, @ovar{action-if-found}, @ovar{action-if-not-found})
 Check whether Libgpg-error (at least version @var{minimum-version}, if
 given) exists on the host system.  If it is found, execute
 @var{action-if-found}, otherwise do @var{action-if-not-found}, if
 given.
 
 Additionally, the function defines @code{GPG_ERROR_CFLAGS} to the
 flags needed for compilation of the program to find the
 @file{gpg-error.h} header file, and @code{GPG_ERROR_LIBS} to the
 linker flags needed to link the program to the Libgpg-error library.
 
 This macro searches for @command{gpgrt-config} along the PATH.
 
 @end defmac
 
 You can use the defined Autoconf variables like this in your
 @file{Makefile.am}:
 
 @example
 AM_CPPFLAGS = $(GPG_ERROR_CFLAGS)
 LDADD = $(GPG_ERROR_LIBS)
 @end example
 
 @node Initializing the library
 @section Initializing the library
 
 Before the library can be used, it should initialize itself.  This is
 achieved by invoking the function @code{gpgrt_check_version} described
 below.
 
 Also, it is often desirable to check that the version of
 Libgpg-error used is indeed one which fits all requirements.
 Even with binary compatibility, new features may have been introduced,
 but due to problem with the dynamic linker an old version may actually
 be used.  So you may want to check that the version is okay right
 after program startup.
 
 @deftypefun {const char *} gpgrt_check_version (const char *@var{req_version})
 
 The function @code{gpgrt_check_version} initializes some subsystems used
 by Libgpg-error and must be invoked before any other function in the
 library.
 @xref{Multi-Threading}.
 
 Furthermore, this function returns the version number of the library.
 It can also verify that the version number is higher than a certain
 required version number @var{req_version}, if this value is not a null
 pointer.
 @end deftypefun
 
 
 @node Multi-Threading
 @section Multi-Threading
 
 TBD.
 
 @c **********************************************************
 @c *******************  General  ****************************
 @c **********************************************************
 @node Generalities
 @chapter Generalities
 
 TBD.  (Description of the error function may be taken from Libgcrypt.)
 
 
 
 @c **********************************************************
 @c *********************  Tools  ****************************
 @c **********************************************************
 @node Tools
 @chapter Tools
 
 @menu
 * gpg-error-config::    Print required compiler flags
+* gpgrt-config::    Helper tool for querying installed libraries
 @end menu
 
 @c The original version of this man page has been written for Debian and was
 @c contributed to libgpg-error by Daniel Kahn Gillmor <dkg@fifthhorseman.net>.
 @manpage gpg-error-config.1
 @node gpg-error-config
 @section Print required compiler flags
 @ifset manverb
 .B gpg-error-config
 \- Script to get information about the installed version of libgpg-error
 @end ifset
 
 @mansect synopsis
 @ifset manverb
 .B  gpg-error-config
 .RI [ options ]
 @end ifset
 
 @mansect description
 @command{gpg-error-config} is a tool that is used to configure to
 determine the compiler and linker flags that should be used to compile
 and link programs that use Libgpg-error.
 
 This tool is now obsolete.  Instead, please use pkg-config with
 gpg-error.pc for your new program, or use gpg-error.m4 which uses
 gpgrt-config and gpg-error.pc internally.
 
 @mansect options
 @noindent
 @command{gpg-error-config} accepts the following options:
 
 @table @gnupgtabopt
 
 @item  --mt
 Provide output appropriate for multithreaded programs.  @option{--mt}
 is only useful when combined with other options, and must be the first
 option if present.
 
 @item --version
 Print the currently installed version of Libgpg-error on the
 standard output.
 
 @item --libs
 Print the linker flags that are necessary to link a program using
 Libgpg-error.
 
 @item --cflags
 Print the compiler flags that are necessary to compile a program using
 Libgpg-error.
 
 @item --prefix=@var{prefix}
 If specified, use @var{prefix} instead of the installation prefix that
 Libgpg-error was built with when computing the output for the
 @option{--cflags} and @option{--libs} options.  This option is also
 used for the exec prefix if @option{--exec-prefix} was not specified.
 This option must be specified before any @option{--libs} or
 @code{--cflags} options.
 
 @item --exec-prefix=@var{prefix}
 If specified, use @var{prefix} instead of the installation exec prefix
 that Libgpg-error was built with when computing the output for the
 @option{--cflags} and @option{--libs} options.  This option must be
 specified before any @option{--libs} or @option{--cflags} options.
 
 @end table
 
 @manpause
 
+@manpage gpgrt-config.1
+@node gpgrt-config
+@section gpgrt-config - Helper tool for querying installed libraries.
+@ifset manverb
+.B gpgrt-config
+\- Helper script to get information about the installed version of gpg libraries
+@end ifset
+
+@mansect synopsis
+@ifset manverb
+.B  gpgrt-config
+.RI [ options ]
+.I [ module ]
+@end ifset
+
+@mansect description
+@command{gpgrt-config} is a script tool that is used by the autoconf macros
+shipped with gnupg software (e.g. AM_PATH_GPG_ERROR and AM_PATH_GPGME) to
+determine the compiler and linker flags that should be used to compile
+and link programs that use the specific library (e.g. libgpg-error or
+libgpgme). @command{gpgrt-config} uses pkg-config .pc files as data source.
+
+Apart from options @command{gpgrt-config} accepts a single argument
+@option{module} specifying the basename (without the ".pc"-suffix) of the
+pkg-config file to be used as input. @option{module} will default to
+@option{gpg-error} if it is not specified.
+
+@mansect options
+@noindent
+@command{gpgrt-config} accepts the following options:
+
+@table @gnupgtabopt
+@item --libdir=@var{LIBDIR}
+Parent directory path of pkgconfig file search path.
+e.g. @samp{gpgrt-config --libdir=/usr/lib --exists gpgme}
+will parse @file{/usr/lib/pkgconfig/gpgme.pc}.
+
+@item  --exists
+Test whether the pkg-config file @file{module.pc} exist and exits with
+success or error accordingly.
+
+@item --modversion
+Print the currently installed version of @option{module} on the standard output.
+
+@item --libs
+Print the linker flags that are necessary to link a program using the
+@option{module}.
+
+@item --cflags
+Print the compiler flags that are necessary to compile a program using the
+@option{module}.
+
+@item --static
+Modifies output if linking statically instead of dynamically.
+
+@item --variable=@var{VARNAME}
+Output variable VARNAME from the module's pkg-config file.
+
+@end table
+
+@mansect bugs
+@noindent
+@command{gpgrt-config} is tried to be compatible to pkg-config, and to
+support cross build well, but it is not intended to be a replacement.
+
+@manpause
 
 
 @c **********************************************************
 @c *************  Appendices (license etc.)  ****************
 @c **********************************************************
 @include lgpl.texi
 
 @include gpl.texi
 
 @c @node Figures and Tables
 @c #@unnumbered List of Figures and Tables
 @c
 @c @listoffloats Figure
 @c
 @c @listoffloats Table
 
 @node Concept Index
 @unnumbered Concept Index
 
 @printindex cp
 
 @node Function and Data Index
 @unnumbered Function and Data Index
 
 @printindex fn
 
 
 @bye