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![Ævar Arnfjörð Bjarmason](/assets/img/avatar_default.png)
Remove the PPC_SHA1 implementation added ina6ef3518f9
([PATCH] PPC assembly implementation of SHA1, 2005-04-22). When this was added Apple consumer hardware used the PPC architecture, and the implementation was intended to improve SHA-1 speed there. Since it was added we've moved to using sha1collisiondetection by default, and anyone wanting hard-rolled non-DC SHA-1 implementation can use OpenSSL's via the OPENSSL_SHA1 knob. The PPC_SHA1 originally originally targeted 32 bit PPC, and later the 64 bit PPC 970 (a.k.a. Apple PowerPC G5). See926172c5e4
(block-sha1: improve code on large-register-set machines, 2009-08-10) for a reference about the performance on G5 (a comment in block-sha1/sha1.c being removed here). I can't get it to do anything but segfault on both the BE and LE POWER machines in the GCC compile farm[1]. Anyone who's concerned about performance on PPC these days is likely to be using the IBM POWER processors. There have been proposals to entirely remove non-sha1collisiondetection implementations from the tree[2]. I think per [3] that would be a bit overzealous. I.e. there are various set-ups git's speed is going to be more important than the relatively implausible SHA-1 collision attack, or where such attacks are entirely mitigated by other means (e.g. by incoming objects being checked with DC_SHA1). But that really doesn't apply to PPC_SHA1 in particular, which seems to have outlived its usefulness. As this gets rid of the only in-tree *.S assembly file we can remove the small bits of logic from the Makefile needed to build objects from *.S (as opposed to *.c) The code being removed here was also throwing warnings with the "-pedantic" flag, it could have been fixed as544d93bc3b
(block-sha1: remove use of obsolete x86 assembly, 2022-03-10) did for block-sha1/*, but as noted above let's remove it instead. 1. https://cfarm.tetaneutral.net/machines/list/ Tested on gcc{110,112,135,203}, a mixture of POWER [789] ppc64 and ppc64le. All segfault in anything needing object hashing (e.g. t/t1007-hash-object.sh) when compiled with PPC_SHA1=Y. 2. https://lore.kernel.org/git/20200223223758.120941-1-mh@glandium.org/ 3. https://lore.kernel.org/git/20200224044732.GK1018190@coredump.intra.peff.net/ Acked-by: brian m. carlson" <sandals@crustytoothpaste.net> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
246 lines
9.9 KiB
Plaintext
246 lines
9.9 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
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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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Alternatively you can run profile feedback only with the git benchmark
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suite. This runs significantly faster than the full test suite, but
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has less coverage:
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$ make prefix=/usr profile-fast
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# make prefix=/usr PROFILE=BUILD install
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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-install
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or
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$ make profile-fast-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/build/lib
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export GIT_EXEC_PATH PATH GITPERLLIB
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- By default (unless NO_PERL is provided) Git will ship various perl
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scripts. However, for simplicity it doesn't use the
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ExtUtils::MakeMaker toolchain to decide where to place the perl
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libraries. Depending on the system this can result in the perl
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libraries not being where you'd like them if they're expected to be
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used by things other than Git itself.
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Manually supplying a perllibdir prefix should fix this, if this is
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a problem you care about, e.g.:
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prefix=/usr perllibdir=/usr/$(/usr/bin/perl -MConfig -wle 'print substr $Config{installsitelib}, 1 + length $Config{siteprefixexp}')
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Will result in e.g. perllibdir=/usr/share/perl/5.26.1 on Debian,
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perllibdir=/usr/share/perl5 (which we'd use by default) on CentOS.
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- Unless NO_PERL is provided Git will ship various perl libraries it
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needs. Distributors of Git will usually want to set
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NO_PERL_CPAN_FALLBACKS if NO_PERL is not provided to use their own
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copies of the CPAN modules Git needs.
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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 appropriate "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 some scripts needed
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for everyday use (e.g. "bisect", "request-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. Digest::MD5, File::Spec, File::Temp, Net::Domain,
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Net::SMTP, and Time::HiRes.
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- git-imap-send needs the OpenSSL library to talk IMAP over SSL if
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you are using libcurl older than 7.34.0. Otherwise you can use
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NO_OPENSSL without losing git-imap-send.
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By default, git uses OpenSSL for SHA1 but it will use its own
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library (inspired by Mozilla's) with either NO_OPENSSL or
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BLK_SHA1.
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- "libcurl" library is used for fetching and pushing
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repositories over http:// or https://, as well as by
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git-imap-send if the curl version is >= 7.34.0. If you do
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not need that functionality, use NO_CURL to build without
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it.
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Git requires version "7.19.4" or later of "libcurl" to build
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without NO_CURL. This version requirement may be bumped in
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the future.
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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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- Python version 2.7 or later is needed to use the git-p4 interface
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to Perforce.
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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 is known to work.
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All formats require at least asciidoc 8.4.1. Alternatively, you can
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use Asciidoctor (requires Ruby) by passing USE_ASCIIDOCTOR=YesPlease
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to make. You need at least Asciidoctor version 1.5.
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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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The minimum supported version of docbook-xsl is 1.74.
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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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