INSTALL

   1
   2 XZ Utils Installation
   3 =====================
   4
   5     0. Preface
   6     1. Supported platforms
   7        1.1. Compilers
   8        1.2. Platform-specific notes
   9             1.2.1. AIX
  10             1.2.2. IRIX
  11             1.2.3. MINIX 3
  12             1.2.4. OpenVMS
  13             1.2.5. Solaris, OpenSolaris, and derivatives
  14             1.2.6. Tru64
  15             1.2.7. Windows
  16             1.2.8. DOS
  17             1.2.9. z/OS
  18        1.3. Adding support for new platforms
  19     2. configure options
  20        2.1. Static vs. dynamic linking of liblzma
  21        2.2. Optimizing xzdec and lzmadec
  22     3. xzgrep and other scripts
  23        3.1. Dependencies
  24        3.2. PATH
  25     4. Tests
  26        4.1 Testing in parallel
  27        4.2 Cross compiling
  28     5. Troubleshooting
  29        5.1. "No C99 compiler was found."
  30        5.2. "No POSIX conforming shell (sh) was found."
  31        5.3. configure works but build fails at crc32_x86.S
  32        5.4. Lots of warnings about symbol visibility
  33        5.5. "make check" fails
  34        5.6. liblzma.so (or similar) not found when running xz
  35
  36
  37 0. Preface
  38 ----------
  39
  40     If you aren't familiar with building packages that use GNU Autotools,
  41     see the file INSTALL.generic for generic instructions before reading
  42     further.
  43
  44     If you are going to build a package for distribution, see also the
  45     file PACKAGERS. It contains information that should help making the
  46     binary packages as good as possible, but the information isn't very
  47     interesting to those making local builds for private use or for use
  48     in special situations like embedded systems.
  49
  50
  51 1. Supported platforms
  52 ----------------------
  53
  54     XZ Utils are developed on GNU/Linux, but they should work on many
  55     POSIX-like operating systems like *BSDs and Solaris, and even on
  56     a few non-POSIX operating systems.
  57
  58
  59 1.1. Compilers
  60
  61     A C99 compiler is required to compile XZ Utils. If you use GCC, you
  62     need at least version 3.x.x. GCC version 2.xx.x doesn't support some
  63     C99 features used in XZ Utils source code, thus GCC 2 won't compile
  64     XZ Utils.
  65
  66     XZ Utils takes advantage of some GNU C extensions when building
  67     with GCC. Because these extensions are used only when building
  68     with GCC, it should be possible to use any C99 compiler.
  69
  70
  71 1.2. Platform-specific notes
  72
  73 1.2.1. AIX
  74
  75     If you use IBM XL C compiler, pass CC=xlc_r to configure. If
  76     you use CC=xlc instead, you must disable threading support
  77     with --disable-threads (usually not recommended).
  78
  79
  80 1.2.2. IRIX
  81
  82     MIPSpro 7.4.4m has been reported to produce broken code if using
  83     the -O2 optimization flag ("make check" fails). Using -O1 should
  84     work.
  85
  86     A problem has been reported when using shared liblzma. Passing
  87     --disable-shared to configure works around this. Alternatively,
  88     putting "-64" to CFLAGS to build a 64-bit version might help too.
  89
  90
  91 1.2.3. MINIX 3
  92
  93     The default install of MINIX 3 includes Amsterdam Compiler Kit (ACK),
  94     which doesn't support C99. Install GCC to compile XZ Utils.
  95
  96     MINIX 3.1.8 and older have bugs in /usr/include/stdint.h, which has
  97     to be patched before XZ Utils can be compiled correctly. See
  98     <http://gforge.cs.vu.nl/gf/project/minix/tracker/?action=TrackerItemEdit&tracker_item_id=537>.
  99
 100     MINIX 3.2.0 and later use a different libc and aren't affected by
 101     the above bug.
 102
 103     XZ Utils doesn't have code to detect the amount of physical RAM and
 104     number of CPU cores on MINIX 3.
 105
 106     See section 5.4 in this file about symbol visibility warnings (you
 107     may want to pass gl_cv_cc_visibility=no to configure).
 108
 109
 110 1.2.4. OpenVMS
 111
 112     XZ Utils can be built for OpenVMS, but the build system files
 113     are not included in the XZ Utils source package. The required
 114     OpenVMS-specific files are maintained by Jouk Jansen and can be
 115     downloaded here:
 116
 117         http://nchrem.tnw.tudelft.nl/openvms/software2.html#xzutils
 118
 119
 120 1.2.5. Solaris, OpenSolaris, and derivatives
 121
 122     The following linker error has been reported on some x86 systems:
 123
 124         ld: fatal: relocation error: R_386_GOTOFF: ...
 125
 126     This can be worked around by passing gl_cv_cc_visibility=no
 127     as an argument to the configure script.
 128
 129     test_scripts.sh in "make check" may fail if good enough tools are
 130     missing from PATH (/usr/xpg4/bin or /usr/xpg6/bin). Nowadays
 131     /usr/xpg4/bin is added to the script PATH by default on Solaris
 132     (see --enable-path-for-scripts=PREFIX in section 2), but old xz
 133     releases needed extra steps. See sections 5.5 and 3.2 for more
 134     information.
 135
 136
 137 1.2.6. Tru64
 138
 139     If you try to use the native C compiler on Tru64 (passing CC=cc to
 140     configure), you may need the workaround mention in section 5.1 in
 141     this file (pass also ac_cv_prog_cc_c99= to configure).
 142
 143
 144 1.2.7. Windows
 145
 146     If it is enough to build liblzma (no command line tools):
 147
 148       - There is CMake support. It should be good enough to build
 149         static liblzma or liblzma.dll with Visual Studio. The CMake
 150         support may work with MinGW or MinGW-w64. Read the comment
 151         in the beginning of CMakeLists.txt before running CMake!
 152
 153       - There are Visual Studio project files under the "windows"
 154         directory. See windows/INSTALL-MSVC.txt. In the future the
 155         project files will be removed when CMake support is good
 156         enough. Thus, please test the CMake version and help fix
 157         possible issues.
 158
 159     To build also the command line tools:
 160
 161       - MinGW-w64 + MSYS (32-bit and 64-bit x86): This is used
 162         for building the official binary packages for Windows.
 163         There is windows/build.bash to ease packaging XZ Utils with
 164         MinGW(-w64) + MSYS into a redistributable .zip or .7z file.
 165         See windows/INSTALL-MinGW.txt for more information.
 166
 167       - MinGW + MSYS (32-bit x86): I haven't recently tested this.
 168
 169       - Cygwin 1.7.35 and later: NOTE that using XZ Utils >= 5.2.0
 170         under Cygwin older than 1.7.35 can lead to DATA LOSS! If
 171         you must use an old Cygwin version, stick to XZ Utils 5.0.x
 172         which is safe under older Cygwin versions. You can check
 173         the Cygwin version with the command "cygcheck -V".
 174
 175     It may be possible to build liblzma with other toolchains too, but
 176     that will probably require writing a separate makefile. Building
 177     the command line tools with non-GNU toolchains will be harder than
 178     building only liblzma.
 179
 180     Even if liblzma is built with MinGW(-w64), the resulting DLL can
 181     be used by other compilers and linkers, including MSVC. See
 182     windows/README-Windows.txt for details.
 183
 184
 185 1.2.8. DOS
 186
 187     There is a Makefile in the "dos" directory to build XZ Utils on
 188     DOS using DJGPP. Support for long file names (LFN) is needed at
 189     build time but the resulting xz.exe works without LFN support too.
 190     See dos/INSTALL.txt and dos/README.txt for more information.
 191
 192
 193 1.2.9. z/OS
 194
 195     To build XZ Utils on z/OS UNIX System Services using xlc, pass
 196     these options to the configure script: CC='xlc -qhaltonmsg=CCN3296'
 197     CPPFLAS='-D_UNIX03_THREADS -D_XOPEN_SOURCE=600'. The first makes
 198     xlc throw an error if a header file is missing, which is required
 199     to make the tests in configure work. The CPPFLAGS are needed to
 200     get pthread support (some other CPPFLAGS may work too; if there
 201     are problems, try -D_UNIX95_THREADS instead of -D_UNIX03_THREADS).
 202
 203     test_scripts.sh in "make check" will fail even if the scripts
 204     actually work because the test data includes compressed files
 205     with US-ASCII text.
 206
 207     No other tests should fail. If test_files.sh fails, check that
 208     the included .xz test files weren't affected by EBCDIC conversion.
 209
 210     XZ Utils doesn't have code to detect the amount of physical RAM and
 211     number of CPU cores on z/OS.
 212
 213
 214 1.3. Adding support for new platforms
 215
 216     If you have written patches to make XZ Utils to work on previously
 217     unsupported platform, please send the patches to me! I will consider
 218     including them to the official version. It's nice to minimize the
 219     need of third-party patching.
 220
 221     One exception: Don't request or send patches to change the whole
 222     source package to C89. I find C99 substantially nicer to write and
 223     maintain. However, the public library headers must be in C89 to
 224     avoid frustrating those who maintain programs, which are strictly
 225     in C89 or C++.
 226
 227
 228 2. configure options
 229 --------------------
 230
 231     In most cases, the defaults are what you want. Many of the options
 232     below are useful only when building a size-optimized version of
 233     liblzma or command line tools.
 234
 235     --enable-encoders=LIST
 236     --disable-encoders
 237                 Specify a comma-separated LIST of filter encoders to
 238                 build. See "./configure --help" for exact list of
 239                 available filter encoders. The default is to build all
 240                 supported encoders.
 241
 242                 If LIST is empty or --disable-encoders is used, no filter
 243                 encoders will be built and also the code shared between
 244                 encoders will be omitted.
 245
 246                 Disabling encoders will remove some symbols from the
 247                 liblzma ABI, so this option should be used only when it
 248                 is known to not cause problems.
 249
 250     --enable-decoders=LIST
 251     --disable-decoders
 252                 This is like --enable-encoders but for decoders. The
 253                 default is to build all supported decoders.
 254
 255     --enable-match-finders=LIST
 256                 liblzma includes two categories of match finders:
 257                 hash chains and binary trees. Hash chains (hc3 and hc4)
 258                 are quite fast but they don't provide the best compression
 259                 ratio. Binary trees (bt2, bt3 and bt4) give excellent
 260                 compression ratio, but they are slower and need more
 261                 memory than hash chains.
 262
 263                 You need to enable at least one match finder to build the
 264                 LZMA1 or LZMA2 filter encoders. Usually hash chains are
 265                 used only in the fast mode, while binary trees are used to
 266                 when the best compression ratio is wanted.
 267
 268                 The default is to build all the match finders if LZMA1
 269                 or LZMA2 filter encoders are being built.
 270
 271     --enable-checks=LIST
 272                 liblzma support multiple integrity checks. CRC32 is
 273                 mandatory, and cannot be omitted. See "./configure --help"
 274                 for exact list of available integrity check types.
 275
 276                 liblzma and the command line tools can decompress files
 277                 which use unsupported integrity check type, but naturally
 278                 the file integrity cannot be verified in that case.
 279
 280                 Disabling integrity checks may remove some symbols from
 281                 the liblzma ABI, so this option should be used only when
 282                 it is known to not cause problems.
 283
 284     --enable-external-sha256
 285                 Try to use SHA-256 code from the operating system libc
 286                 or similar base system libraries. This doesn't try to
 287                 use OpenSSL or libgcrypt or such libraries.
 288
 289                 The reasons to use this option:
 290
 291                   - It makes liblzma slightly smaller.
 292
 293                   - It might improve SHA-256 speed if the implementation
 294                     in the operating is very good (but see below).
 295
 296                 External SHA-256 is disabled by default for two reasons:
 297
 298                   - On some operating systems the symbol names of the
 299                     SHA-256 functions conflict with OpenSSL's libcrypto.
 300                     This causes weird problems such as decompression
 301                     errors if an application is linked against both
 302                     liblzma and libcrypto. This problem affects at least
 303                     FreeBSD 10 and older and MINIX 3.3.0 and older, but
 304                     other OSes that provide a function "SHA256_Init" might
 305                     also be affected. FreeBSD 11 has the problem fixed.
 306                     NetBSD had the problem but it was fixed it in 2009
 307                     already. OpenBSD uses "SHA256Init" and thus never had
 308                     a conflict with libcrypto.
 309
 310                   - The SHA-256 code in liblzma is faster than the SHA-256
 311                     code provided by some operating systems. If you are
 312                     curious, build two copies of xz (internal and external
 313                     SHA-256) and compare the decompression (xz --test)
 314                     times:
 315
 316                         dd if=/dev/zero bs=1024k count=1024 \
 317                             | xz -v -0 -Csha256 > foo.xz
 318                         time xz --test foo.xz
 319
 320     --disable-microlzma
 321                 Don't build MicroLZMA encoder and decoder. This omits
 322                 lzma_microlzma_encoder() and lzma_microlzma_decoder()
 323                 API functions from liblzma. These functions are needed
 324                 by specific applications only. They were written for
 325                 erofs-utils but they may be used by others too.
 326
 327     --disable-lzip-decoder
 328                 Disable decompression support for .lz (lzip) files.
 329                 This omits the API function lzma_lzip_decoder() from
 330                 liblzma and .lz support from the xz tool.
 331
 332     --disable-xz
 333     --disable-xzdec
 334     --disable-lzmadec
 335     --disable-lzmainfo
 336                 Don't build and install the command line tool mentioned
 337                 in the option name.
 338
 339                 NOTE: Disabling xz will skip some tests in "make check".
 340
 341                 NOTE: If xzdec is disabled and lzmadec is left enabled,
 342                 a dangling man page symlink lzmadec.1 -> xzdec.1 is
 343                 created.
 344
 345     --disable-lzma-links
 346                 Don't create symlinks for LZMA Utils compatibility.
 347                 This includes lzma, unlzma, and lzcat. If scripts are
 348                 installed, also lzdiff, lzcmp, lzgrep, lzegrep, lzfgrep,
 349                 lzmore, and lzless will be omitted if this option is used.
 350
 351     --disable-scripts
 352                 Don't install the scripts xzdiff, xzgrep, xzmore, xzless,
 353                 and their symlinks.
 354
 355     --disable-doc
 356                 Don't install the documentation files to $docdir
 357                 (often /usr/doc/xz or /usr/local/doc/xz). Man pages
 358                 will still be installed. The $docdir can be changed
 359                 with --docdir=DIR.
 360
 361     --disable-assembler
 362                 liblzma includes some assembler optimizations. Currently
 363                 there is only assembler code for CRC32 and CRC64 for
 364                 32-bit x86.
 365
 366                 All the assembler code in liblzma is position-independent
 367                 code, which is suitable for use in shared libraries and
 368                 position-independent executables. So far only i386
 369                 instructions are used, but the code is optimized for i686
 370                 class CPUs. If you are compiling liblzma exclusively for
 371                 pre-i686 systems, you may want to disable the assembler
 372                 code.
 373
 374     --disable-clmul-crc
 375                 Disable the use of carryless multiplication for CRC
 376                 calculation even if compiler support for it is detected.
 377                 The code uses runtime detection of SSSE3, SSE4.1, and
 378                 CLMUL instructions on x86. On 32-bit x86 this currently
 379                 is used only if --disable-assembler is used (this might
 380                 be fixed in the future). The code works on E2K too.
 381
 382                 If using compiler options that unconditionally allow the
 383                 required extensions (-msse4.1 -mpclmul) then runtime
 384                 detection isn't used and the generic code is omitted.
 385
 386     --disable-arm64-crc32
 387                 Disable the use of the ARM64 CRC32 instruction extension
 388                 even if compiler support for it is detected. The code will
 389                 detect support for the instruction at runtime.
 390
 391                 If using compiler options that unconditionally allow the
 392                 required extensions (-march=armv8-a+crc or -march=armv8.1-a
 393                 and later) then runtime detection isn't used and the
 394                 generic code is omitted.
 395
 396     --enable-unaligned-access
 397                 Allow liblzma to use unaligned memory access for 16-bit,
 398                 32-bit, and 64-bit loads and stores. This should be
 399                 enabled only when the hardware supports this, that is,
 400                 when unaligned access is fast. Some operating system
 401                 kernels emulate unaligned access, which is extremely
 402                 slow. This option shouldn't be used on systems that
 403                 rely on such emulation.
 404
 405                 Unaligned access is enabled by default on these:
 406                   - 32-bit x86
 407                   - 64-bit x86-64
 408                   - 32-bit big endian PowerPC
 409                   - 64-bit big endian PowerPC
 410                   - 64-bit little endian PowerPC
 411                   - some RISC-V [1]
 412                   - some 32-bit ARM [2]
 413                   - some 64-bit ARM64 [2] (NOTE: Autodetection bug
 414                     if using GCC -mstrict-align, see below.)
 415
 416                 [1] Unaligned access is enabled by default if
 417                     configure sees that the C compiler
 418                     #defines __riscv_misaligned_fast.
 419
 420                 [2] Unaligned access is enabled by default if
 421                     configure sees that the C compiler
 422                     #defines __ARM_FEATURE_UNALIGNED:
 423
 424                       - ARMv7 + GCC or Clang: It works. The options
 425                         -munaligned-access and -mno-unaligned-access
 426                         affect this macro correctly.
 427
 428                       - ARM64 + Clang: It works. The options
 429                         -munaligned-access, -mno-unaligned-access,
 430                         and -mstrict-align affect this macro correctly.
 431                         Clang >= 17 supports -mno-strict-align too.
 432
 433                       - ARM64 + GCC: It partially works. The macro
 434                         is always #defined by GCC versions at least
 435                         up to 13.2, even when using -mstrict-align.
 436                         If building for strict-align ARM64, the
 437                         configure option --disable-unaligned-access
 438                         should be used if using a GCC version that has
 439                         this issue because otherwise the performance
 440                         may be degraded. It likely won't crash due to
 441                         how unaligned access is done in the C code.
 442
 443     --enable-unsafe-type-punning
 444                 This enables use of code like
 445
 446                     uint8_t *buf8 = ...;
 447                     *(uint32_t *)buf8 = ...;
 448
 449                 which violates strict aliasing rules and may result
 450                 in broken code. There should be no need to use this
 451                 option with recent GCC or Clang versions on any
 452                 arch as just as fast code can be generated in a safe
 453                 way too (using __builtin_assume_aligned + memcpy).
 454
 455                 However, this option might improve performance in some
 456                 other cases, especially with old compilers (for example,
 457                 GCC 3 and early 4.x on x86, GCC < 6 on ARMv6 and ARMv7).
 458
 459     --enable-small
 460                 Reduce the size of liblzma by selecting smaller but
 461                 semantically equivalent version of some functions, and
 462                 omit precomputed lookup tables. This option tends to
 463                 make liblzma slightly slower.
 464
 465                 Note that while omitting the precomputed tables makes
 466                 liblzma smaller on disk, the tables are still needed at
 467                 run time, and need to be computed at startup. This also
 468                 means that the RAM holding the tables won't be shared
 469                 between applications linked against shared liblzma.
 470
 471                 This option doesn't modify CFLAGS to tell the compiler
 472                 to optimize for size. You need to add -Os or equivalent
 473                 flag(s) to CFLAGS manually.
 474
 475     --enable-assume-ram=SIZE
 476                 On the most common operating systems, XZ Utils is able to
 477                 detect the amount of physical memory on the system. This
 478                 information is used by the options --memlimit-compress,
 479                 --memlimit-decompress, and --memlimit when setting the
 480                 limit to a percentage of total RAM.
 481
 482                 On some systems, there is no code to detect the amount of
 483                 RAM though. Using --enable-assume-ram one can set how much
 484                 memory to assume on these systems. SIZE is given as MiB.
 485                 The default is 128 MiB.
 486
 487                 Feel free to send patches to add support for detecting
 488                 the amount of RAM on the operating system you use. See
 489                 src/common/tuklib_physmem.c for details.
 490
 491     --enable-threads=METHOD
 492                 Threading support is enabled by default so normally there
 493                 is no need to specify this option.
 494
 495                 Supported values for METHOD:
 496
 497                         yes     Autodetect the threading method. If none
 498                                 is found, configure will give an error.
 499
 500                         posix   Use POSIX pthreads. This is the default
 501                                 except on Windows outside Cygwin.
 502
 503                         win95   Use Windows 95 compatible threads. This
 504                                 is compatible with Windows XP and later
 505                                 too. This is the default for 32-bit x86
 506                                 Windows builds. Unless the compiler
 507                                 supports __attribute__((__constructor__)),
 508                                 the 'win95' threading is incompatible with
 509                                 --enable-small.
 510
 511                         vista   Use Windows Vista compatible threads. The
 512                                 resulting binaries won't run on Windows XP
 513                                 or older. This is the default for Windows
 514                                 excluding 32-bit x86 builds (that is, on
 515                                 x86-64 the default is 'vista').
 516
 517                         no      Disable threading support. This is the
 518                                 same as using --disable-threads.
 519                                 NOTE: If combined with --enable-small
 520                                 and the compiler doesn't support
 521                                 __attribute__((__constructor__)), the
 522                                 resulting liblzma won't be thread safe,
 523                                 that is, if a multi-threaded application
 524                                 calls any liblzma functions from more than
 525                                 one thread, something bad may happen.
 526
 527     --enable-ifunc
 528                 Use __attribute__((__ifunc__())) in liblzma. This is
 529                 enabled by default on GNU/Linux and FreeBSD.
 530
 531                 The ifunc attribute is incompatible with
 532                 -fsanitize=address. --disable-ifunc must be used
 533                 if any -fsanitize= option is specified in CFLAGS.
 534
 535     --enable-sandbox=METHOD
 536                 There is limited sandboxing support in the xz and xzdec
 537                 tools. If built with sandbox support, xz uses it
 538                 automatically when (de)compressing exactly one file to
 539                 standard output when the options --files or --files0 aren't
 540                 used. This is a common use case, for example,
 541                 (de)compressing .tar.xz files via GNU tar. The sandbox is
 542                 also used for single-file 'xz --test' or 'xz --list'.
 543                 xzdec always uses the sandbox, except when more than one
 544                 file are decompressed. In this case it will enable the
 545                 sandbox for the last file that is decompressed.
 546
 547                 Supported METHODs:
 548
 549                         auto    Look for a supported sandboxing method
 550                                 and use it if found. If no method is
 551                                 found, then sandboxing isn't used.
 552                                 This is the default.
 553
 554                         no      Disable sandboxing support.
 555
 556                         capsicum
 557                                 Use Capsicum (FreeBSD >= 10.2) for
 558                                 sandboxing. If no Capsicum support
 559                                 is found, configure will give an error.
 560
 561                         pledge  Use pledge(2) (OpenBSD >= 5.9) for
 562                                 sandboxing. If pledge(2) isn't found,
 563                                 configure will give an error.
 564
 565                         landlock
 566                                 Use Landlock (Linux >= 5.13) for
 567                                 sandboxing. If no Landlock support
 568                                 is found, configure will give an error.
 569
 570     --enable-symbol-versions
 571                 Use symbol versioning for liblzma. This is enabled by
 572                 default on GNU/Linux, other GNU-based systems, and
 573                 FreeBSD.
 574
 575     --enable-debug
 576                 This enables the assert() macro and possibly some other
 577                 run-time consistency checks. It makes the code slower, so
 578                 you normally don't want to have this enabled.
 579
 580     --enable-werror
 581                 If building with GCC, make all compiler warnings an error,
 582                 that abort the compilation. This may help catching bugs,
 583                 and should work on most systems. This has no effect on the
 584                 resulting binaries.
 585
 586     --enable-path-for-scripts=PREFIX
 587                 If PREFIX isn't empty, PATH=PREFIX:$PATH will be set in
 588                 the beginning of the scripts (xzgrep and others).
 589                 The default is empty except on Solaris the default is
 590                 /usr/xpg4/bin.
 591
 592                 This can be useful if the default PATH doesn't contain
 593                 modern POSIX tools (as can be the case on Solaris) or if
 594                 one wants to ensure that the correct xz binary is in the
 595                 PATH for the scripts. Note that the latter use can break
 596                 "make check" if the prefixed PATH causes a wrong xz binary
 597                 (other than the one that was just built) to be used.
 598
 599                 Older xz releases support a different method for setting
 600                 the PATH for the scripts. It is described in section 3.2
 601                 and is supported in this xz version too.
 602
 603
 604 2.1. Static vs. dynamic linking of liblzma
 605
 606     On 32-bit x86, linking against static liblzma can give a minor
 607     speed improvement. Static libraries on x86 are usually compiled as
 608     position-dependent code (non-PIC) and shared libraries are built as
 609     position-independent code (PIC). PIC wastes one register, which can
 610     make the code slightly slower compared to a non-PIC version. (Note
 611     that this doesn't apply to x86-64.)
 612
 613     If you want to link xz against static liblzma, the simplest way
 614     is to pass --disable-shared to configure. If you want also shared
 615     liblzma, run configure again and run "make install" only for
 616     src/liblzma.
 617
 618
 619 2.2. Optimizing xzdec and lzmadec
 620
 621     xzdec and lzmadec are intended to be relatively small instead of
 622     optimizing for the best speed. Thus, it is a good idea to build
 623     xzdec and lzmadec separately:
 624
 625       - To link the tools against static liblzma, pass --disable-shared
 626         to configure.
 627
 628       - To select somewhat size-optimized variant of some things in
 629         liblzma, pass --enable-small to configure.
 630
 631       - Tell the compiler to optimize for size instead of speed.
 632         For example, with GCC, put -Os into CFLAGS.
 633
 634       - xzdec and lzmadec will never use multithreading capabilities of
 635         liblzma. You can avoid dependency on libpthread by passing
 636         --disable-threads to configure.
 637
 638       - There are and will be no translated messages for xzdec and
 639         lzmadec, so it is fine to pass also --disable-nls to configure.
 640
 641       - Only decoder code is needed, so you can speed up the build
 642         slightly by passing --disable-encoders to configure. This
 643         shouldn't affect the final size of the executables though,
 644         because the linker is able to omit the encoder code anyway.
 645
 646     If you have no use for xzdec or lzmadec, you can disable them with
 647     --disable-xzdec and --disable-lzmadec.
 648
 649
 650 3. xzgrep and other scripts
 651 ---------------------------
 652
 653 3.1. Dependencies
 654
 655     POSIX shell (sh) and bunch of other standard POSIX tools are required
 656     to run the scripts. The configure script tries to find a POSIX
 657     compliant sh, but if it fails, you can force the shell by passing
 658     gl_cv_posix_shell=/path/to/posix-sh as an argument to the configure
 659     script.
 660
 661     xzdiff (xzcmp/lzdiff/lzcmp) may use mktemp if it is available. As
 662     a fallback xzdiff will use mkdir to securely create a temporary
 663     directory. Having mktemp available is still recommended since the
 664     mkdir fallback method isn't as robust as mktemp is. The original
 665     mktemp can be found from <https://www.mktemp.org/>. On GNU, most will
 666     use the mktemp program from GNU coreutils instead of the original
 667     implementation. Both mktemp versions are fine.
 668
 669     In addition to using xz to decompress .xz files, xzgrep and xzdiff
 670     use gzip, bzip2, and lzop to support .gz, bz2, and .lzo files.
 671
 672
 673 3.2. PATH
 674
 675     The method described below is supported by older xz releases.
 676     It is supported by the current version too, but the newer
 677     --enable-path-for-scripts=PREFIX described in section 2 may be
 678     more convenient.
 679
 680     The scripts assume that the required tools (standard POSIX utilities,
 681     mktemp, and xz) are in PATH; the scripts don't set the PATH themselves
 682     (except as described for --enable-path-for-scripts=PREFIX). Some
 683     people like this while some think this is a bug. Those in the latter
 684     group can easily patch the scripts before running the configure script
 685     by taking advantage of a placeholder line in the scripts.
 686
 687     For example, to make the scripts prefix /usr/bin:/bin to PATH:
 688
 689         perl -pi -e 's|^#SET_PATH.*$|PATH=/usr/bin:/bin:\$PATH|' \
 690                 src/scripts/xz*.in
 691
 692
 693 4. Tests
 694 --------
 695
 696     The test framework can be built and run by executing "make check" in
 697     the build directory. The tests are a mix of executables and POSIX
 698     shell scripts (sh). All tests should pass if the default configuration
 699     is used. Disabling features through the configure options may cause
 700     some tests to be skipped. If any tests do not pass, see section 5.5.
 701
 702
 703 4.1. Testing in parallel
 704
 705     The tests can be run in parallel using the "-j" make option on systems
 706     that support it. For instance, "make -j4 check" will run up to four
 707     tests simultaneously.
 708
 709
 710 4.2. Cross compiling
 711
 712     The tests can be built without running them:
 713
 714         make check TESTS=
 715
 716     The TESTS variable is the list of tests you wish to run. Leaving it
 717     empty will compile the tests without running any.
 718
 719     If the tests are copied to a target machine to execute, the test data
 720     files in the directory tests/files must also be copied. The tests
 721     search for the data files using the environment variable $srcdir,
 722     expecting to find the data files under $srcdir/files/. If $srcdir
 723     isn't set then it defaults to the current directory.
 724
 725     The shell script tests can be copied from the source directory to the
 726     target machine to execute. In addition to the test files, these tests
 727     will expect the following relative file paths to execute properly:
 728
 729         ./create_compress_files
 730         ../config.h
 731         ../src/xz/xz
 732         ../src/xzdec/xzdec
 733         ../src/scripts/xzdiff
 734         ../src/scripts/xzgrep
 735
 736
 737 5. Troubleshooting
 738 ------------------
 739
 740 5.1. "No C99 compiler was found."
 741
 742     You need a C99 compiler to build XZ Utils. If the configure script
 743     cannot find a C99 compiler and you think you have such a compiler
 744     installed, set the compiler command by passing CC=/path/to/c99 as
 745     an argument to the configure script.
 746
 747     If you get this error even when you think your compiler supports C99,
 748     you can override the test by passing ac_cv_prog_cc_c99= as an argument
 749     to the configure script. The test for C99 compiler is not perfect (and
 750     it is not as easy to make it perfect as it sounds), so sometimes this
 751     may be needed. You will get a compile error if your compiler doesn't
 752     support enough C99.
 753
 754
 755 5.2. "No POSIX conforming shell (sh) was found."
 756
 757     xzgrep and other scripts need a shell that (roughly) conforms
 758     to POSIX. The configure script tries to find such a shell. If
 759     it fails, you can force the shell to be used by passing
 760     gl_cv_posix_shell=/path/to/posix-sh as an argument to the configure
 761     script. Alternatively you can omit the installation of scripts and
 762     this error by passing --disable-scripts to configure.
 763
 764
 765 5.3. configure works but build fails at crc32_x86.S
 766
 767     The easy fix is to pass --disable-assembler to the configure script.
 768
 769     The configure script determines if assembler code can be used by
 770     looking at the configure triplet; there is currently no check if
 771     the assembler code can actually actually be built. The x86 assembler
 772     code should work on x86 GNU/Linux, *BSDs, Solaris, Darwin, MinGW,
 773     Cygwin, and DJGPP. On other x86 systems, there may be problems and
 774     the assembler code may need to be disabled with the configure option.
 775
 776     If you get this error when building for x86-64, you have specified or
 777     the configure script has misguessed your architecture. Pass the
 778     correct configure triplet using the --build=CPU-COMPANY-SYSTEM option
 779     (see INSTALL.generic).
 780
 781
 782 5.4. Lots of warnings about symbol visibility
 783
 784     On some systems where symbol visibility isn't supported, GCC may
 785     still accept the visibility options and attributes, which will make
 786     configure think that visibility is supported. This will result in
 787     many compiler warnings. You can avoid the warnings by forcing the
 788     visibility support off by passing gl_cv_cc_visibility=no as an
 789     argument to the configure script. This has no effect on the
 790     resulting binaries, but fewer warnings looks nicer and may allow
 791     using --enable-werror.
 792
 793
 794 5.5. "make check" fails
 795
 796     If the other tests pass but test_scripts.sh fails, then the problem
 797     is in the scripts in src/scripts. Comparing the contents of
 798     tests/xzgrep_test_output to tests/xzgrep_expected_output might
 799     give a good idea about problems in xzgrep. One possibility is that
 800     some tools are missing from the current PATH or the tools lack
 801     support for some POSIX features. This can happen at least on
 802     Solaris where the tools in /bin may be ancient but good enough
 803     tools are available in /usr/xpg4/bin or /usr/xpg6/bin. For possible
 804     fixes, see --enable-path-for-scripts=PREFIX in section 2 and the
 805     older alternative method described in section 3.2 of this file.
 806
 807     If tests other than test_scripts.sh fail, a likely reason is that
 808     libtool links the test programs against an installed version of
 809     liblzma instead of the version that was just built. This is
 810     obviously a bug which seems to happen on some platforms.
 811     A workaround is to uninstall the old liblzma versions first.
 812
 813     If the problem isn't any of those described above, then it's likely
 814     a bug in XZ Utils or in the compiler. See the platform-specific
 815     notes in this file for possible known problems. Please report
 816     a bug if you cannot solve the problem. See README for contact
 817     information.
 818
 819
 820 5.6. liblzma.so (or similar) not found when running xz
 821
 822     If you installed the package with "make install" and get an error
 823     about liblzma.so (or a similarly named file) being missing, try
 824     running "ldconfig" to update the run-time linker cache (if your
 825     operating system has such a command).
 826