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![Theodore Ts'o](/assets/img/avatar_default.png)
There was a number of problems I ran into when trying the
profile-directed optimizations added by Andi Kleen in git commit
7ddc2710b9
. (This was using gcc 4.4 found on many enterprise
distros.)
1) The -fprofile-generate and -fprofile-use commands are incompatible
with ccache; the code ends up looking in the wrong place for the gcda
files based on the ccache object names.
2) If the makefile notices that CFLAGS are different, it will rebuild
all of the binaries. Hence the recipe originally specified by the
INSTALL file ("make profile-all" followed by "make install") doesn't
work. It will appear to work, but the binaries will end up getting
built with no optimization.
This patch fixes this by using an explicit set of options passed via
the PROFILE variable then using this to directly manipulate CFLAGS and
EXTLIBS.
The developer can run "make PROFILE=BUILD all ; sudo make
PROFILE=BUILD install" automatically run a two-pass build with the
test suite run in between as the sample workload for the purpose of
recording profiling information to do the profile-directed
optimization.
Alternatively, the profiling version of binaries can be built using:
make PROFILE=GEN PROFILE_DIR=/var/cache/profile all
make PROFILE=GEN install
and then after git has been used for a while, the optimized version of
the binary can be built as follows:
make PROFILE=USE PROFILE_DIR=/var/cache/profile all
make PROFILE=USE install
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
209 lines
8.5 KiB
Plaintext
209 lines
8.5 KiB
Plaintext
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Git installation
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Normally you can just do "make" followed by "make install", and that
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will install the git programs in your own ~/bin/ directory. If you want
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to do a global install, you can do
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$ make prefix=/usr all doc info ;# as yourself
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# make prefix=/usr install install-doc install-html install-info ;# as root
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(or prefix=/usr/local, of course). Just like any program suite
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that uses $prefix, the built results have some paths encoded,
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which are derived from $prefix, so "make all; make prefix=/usr
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install" would not work.
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The beginning of the Makefile documents many variables that affect the way
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git is built. You can override them either from the command line, or in a
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config.mak file.
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Alternatively you can use autoconf generated ./configure script to
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set up install paths (via config.mak.autogen), so you can write instead
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$ make configure ;# as yourself
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$ ./configure --prefix=/usr ;# as yourself
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$ make all doc ;# as yourself
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# make install install-doc install-html;# as root
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If you're willing to trade off (much) longer build time for a later
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faster git you can also do a profile feedback build with
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$ make prefix=/usr PROFILE=BUILD all
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# make prefix=/usr PROFILE=BUILD install
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This will run the complete test suite as training workload and then
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rebuild git with the generated profile feedback. This results in a git
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which is a few percent faster on CPU intensive workloads. This
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may be a good tradeoff for distribution packagers.
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Or if you just want to install a profile-optimized version of git into
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your home directory, you could run:
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$ make PROFILE=BUILD install
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As a caveat: a profile-optimized build takes a *lot* longer since the
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git tree must be built twice, and in order for the profiling
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measurements to work properly, ccache must be disabled and the test
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suite has to be run using only a single CPU. In addition, the profile
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feedback build stage currently generates a lot of additional compiler
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warnings.
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Issues of note:
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- Ancient versions of GNU Interactive Tools (pre-4.9.2) installed a
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program "git", whose name conflicts with this program. But with
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version 4.9.2, after long hiatus without active maintenance (since
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around 1997), it changed its name to gnuit and the name conflict is no
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longer a problem.
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NOTE: When compiled with backward compatibility option, the GNU
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Interactive Tools package still can install "git", but you can build it
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with --disable-transition option to avoid this.
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- You can use git after building but without installing if you want
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to test drive it. Simply run git found in bin-wrappers directory
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in the build directory, or prepend that directory to your $PATH.
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This however is less efficient than running an installed git, as
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you always need an extra fork+exec to run any git subcommand.
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It is still possible to use git without installing by setting a few
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environment variables, which was the way this was done
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traditionally. But using git found in bin-wrappers directory in
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the build directory is far simpler. As a historical reference, the
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old way went like this:
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GIT_EXEC_PATH=`pwd`
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PATH=`pwd`:$PATH
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GITPERLLIB=`pwd`/perl/blib/lib
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export GIT_EXEC_PATH PATH GITPERLLIB
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- Git is reasonably self-sufficient, but does depend on a few external
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programs and libraries. Git can be used without most of them by adding
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the approriate "NO_<LIBRARY>=YesPlease" to the make command line or
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config.mak file.
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- "zlib", the compression library. Git won't build without it.
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- "ssh" is used to push and pull over the net.
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- A POSIX-compliant shell is required to run many scripts needed
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for everyday use (e.g. "bisect", "pull").
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- "Perl" version 5.8 or later is needed to use some of the
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features (e.g. preparing a partial commit using "git add -i/-p",
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interacting with svn repositories with "git svn"). If you can
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live without these, use NO_PERL. Note that recent releases of
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Redhat/Fedora are reported to ship Perl binary package with some
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core modules stripped away (see http://lwn.net/Articles/477234/),
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so you might need to install additional packages other than Perl
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itself, e.g. Time::HiRes.
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- "openssl" library is used by git-imap-send to use IMAP over SSL.
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If you don't need it, use NO_OPENSSL.
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By default, git uses OpenSSL for SHA1 but it will use it's own
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library (inspired by Mozilla's) with either NO_OPENSSL or
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BLK_SHA1. Also included is a version optimized for PowerPC
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(PPC_SHA1).
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- "libcurl" library is used by git-http-fetch and git-fetch. You
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might also want the "curl" executable for debugging purposes.
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If you do not use http:// or https:// repositories, you do not
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have to have them (use NO_CURL).
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- "expat" library; git-http-push uses it for remote lock
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management over DAV. Similar to "curl" above, this is optional
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(with NO_EXPAT).
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- "wish", the Tcl/Tk windowing shell is used in gitk to show the
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history graphically, and in git-gui. If you don't want gitk or
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git-gui, you can use NO_TCLTK.
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- A gettext library is used by default for localizing Git. The
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primary target is GNU libintl, but the Solaris gettext
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implementation also works.
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We need a gettext.h on the system for C code, gettext.sh (or
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Solaris gettext(1)) for shell scripts, and libintl-perl for Perl
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programs.
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Set NO_GETTEXT to disable localization support and make Git only
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use English. Under autoconf the configure script will do this
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automatically if it can't find libintl on the system.
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- Some platform specific issues are dealt with Makefile rules,
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but depending on your specific installation, you may not
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have all the libraries/tools needed, or you may have
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necessary libraries at unusual locations. Please look at the
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top of the Makefile to see what can be adjusted for your needs.
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You can place local settings in config.mak and the Makefile
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will include them. Note that config.mak is not distributed;
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the name is reserved for local settings.
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- To build and install documentation suite, you need to have
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the asciidoc/xmlto toolchain. Because not many people are
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inclined to install the tools, the default build target
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("make all") does _not_ build them.
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"make doc" builds documentation in man and html formats; there are
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also "make man", "make html" and "make info". Note that "make html"
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requires asciidoc, but not xmlto. "make man" (and thus make doc)
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requires both.
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"make install-doc" installs documentation in man format only; there
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are also "make install-man", "make install-html" and "make
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install-info".
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Building and installing the info file additionally requires
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makeinfo and docbook2X. Version 0.8.3 is known to work.
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Building and installing the pdf file additionally requires
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dblatex. Version 0.2.7 with asciidoc >= 8.2.7 is known to work.
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The documentation is written for AsciiDoc 7, but by default
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uses some compatibility wrappers to work on AsciiDoc 8. If you have
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AsciiDoc 7, try "make ASCIIDOC7=YesPlease".
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There are also "make quick-install-doc", "make quick-install-man"
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and "make quick-install-html" which install preformatted man pages
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and html documentation. To use these build targets, you need to
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clone two separate git-htmldocs and git-manpages repositories next
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to the clone of git itself.
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It has been reported that docbook-xsl version 1.72 and 1.73 are
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buggy; 1.72 misformats manual pages for callouts, and 1.73 needs
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the patch in contrib/patches/docbook-xsl-manpages-charmap.patch
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Users attempting to build the documentation on Cygwin may need to ensure
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that the /etc/xml/catalog file looks something like this:
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<?xml version="1.0"?>
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<!DOCTYPE catalog PUBLIC
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"-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
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"http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"
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>
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<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog">
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<rewriteURI
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uriStartString = "http://docbook.sourceforge.net/release/xsl/current"
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rewritePrefix = "/usr/share/sgml/docbook/xsl-stylesheets"
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/>
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<rewriteURI
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uriStartString="http://www.oasis-open.org/docbook/xml/4.5"
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rewritePrefix="/usr/share/sgml/docbook/xml-dtd-4.5"
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/>
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</catalog>
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This can be achieved with the following two xmlcatalog commands:
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xmlcatalog --noout \
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--add rewriteURI \
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http://docbook.sourceforge.net/release/xsl/current \
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/usr/share/sgml/docbook/xsl-stylesheets \
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/etc/xml/catalog
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xmlcatalog --noout \
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--add rewriteURI \
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http://www.oasis-open.org/docbook/xml/4.5/xsl/current \
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/usr/share/sgml/docbook/xml-dtd-4.5 \
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/etc/xml/catalog
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