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1 | 1 |
2 Information to packagers of XZ Utils | 2 Information to packagers of XZ Utils |
3 ==================================== | 3 ==================================== |
4 | 4 |
5 0. Preface | 5 0. Preface |
6 1. Package naming | 6 1. Package naming |
7 2. Package description | 7 2. Package description |
8 3. License | 8 3. License |
9 4. configure options | 9 4. configure options |
10 4.1. Static vs. dynamic linking of liblzma | |
11 4.2. Optimizing xzdec and lzmadec | |
12 5. Additional documentation | 10 5. Additional documentation |
13 6. Extra files | 11 6. Extra files |
14 7. Installing XZ Utils and LZMA Utils in parallel | 12 7. Installing XZ Utils and LZMA Utils in parallel |
15 8. Example | 13 8. Example |
16 | 14 |
17 | 15 |
18 0. Preface | 16 0. Preface |
19 ---------- | 17 ---------- |
20 | 18 |
21 This document is meant for people who create and maintain XZ Utils | 19 This document is meant for people who create and maintain XZ Utils |
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134 only for embedded systems, don't use the following configure options: | 132 only for embedded systems, don't use the following configure options: |
135 | 133 |
136 --enable-debug | 134 --enable-debug |
137 --enable-encoders (*) | 135 --enable-encoders (*) |
138 --enable-decoders | 136 --enable-decoders |
139 --enable-match-finders | 137 --enable-match-finders |
140 --enable-checks | 138 --enable-checks |
141 --enable-small (*) | 139 --enable-small (*) |
142 --disable-threads (*) | 140 --disable-threads (*) |
143 | 141 |
144 (*) These are OK when building xzdec and lzmadec as explained later. | 142 (*) These are OK when building xzdec and lzmadec as described |
| 143 in INSTALL. |
145 | 144 |
146 You may use --enable-werror but be careful with it since it may break | 145 xzdec and lzmadec don't provide any functionality that isn't already |
147 the build due to some useless warning when the build environment | 146 available in the xz tool. Shipping xzdec and lzmadec without size |
148 changes (like CPU architecture or compiler version). | 147 optimization and statically-linked liblzma isn't very useful. Doing |
149 | 148 that would give users the xzdec man page, which may make it easier |
150 | 149 for people to find out that such tools exists, but the executables |
151 4.1. Static vs. dynamic linking of liblzma | 150 wouldn't have any advantage over the full-featured xz. |
152 | |
153 The default is to link the most important command line tools against | |
154 static liblzma, and the less important tools against shared liblzma. | |
155 This can be changed by passing --enable-dynamic to configure, or by | |
156 not building static libraries at all by passing --disable-static | |
157 to configure. It is mildly recommended that you use the default, but | |
158 the configure options make it easy to do otherwise if the distro policy | |
159 so requires. | |
160 | |
161 On 32-bit x86, linking against static liblzma can give a minor | |
162 speed improvement. Static libraries on x86 are usually compiled as | |
163 position-dependent code (non-PIC) and shared libraries are built as | |
164 position-independent code (PIC). PIC wastes one register, which can | |
165 make the code slightly slower compared to a non-PIC version. (Note | |
166 that this doesn't apply to x86-64.) | |
167 | |
168 Linking against static liblzma avoids a dependency on liblzma shared | |
169 library, and makes it slightly easier to copy the command line tools | |
170 between systems (e.g. quick 'n' dirty emergency recovery of some | |
171 files). It also allows putting the command line tools to /bin while | |
172 leaving liblzma to /usr/lib (assuming that your distribution uses | |
173 such a file system hierarchy), if no other file in /bin would require | |
174 liblzma. | |
175 | |
176 If you don't want to distribute static libraries but you still | |
177 want to link the command line tools against static liblzma, it is | |
178 probably easiest to build both static and shared liblzma, but after | |
179 "make DESTDIR=$PKG install" remove liblzma.a and modify liblzma.la | |
180 to not contain a reference to liblzma.a. | |
181 | |
182 | |
183 4.2. Optimizing xzdec and lzmadec | |
184 | |
185 xzdec and lzmadec are intended to be relatively small instead of | |
186 optimizing for the best speed. Thus, it is a good idea to build | |
187 xzdec and lzmadec separately: | |
188 | |
189 - Only decoder code is needed, so you can speed up the build | |
190 slightly by passing --disable-encoders to configure. This | |
191 shouldn't affect the final size of the executables though, | |
192 because the linker is able to omit the encoder code anyway. | |
193 | |
194 - xzdec and lzmadec will never use multithreading capabilities of | |
195 liblzma. You can avoid dependency on libpthread by passing | |
196 --disable-threads to configure. | |
197 | |
198 - There are and will be no translated messages for xzdec and | |
199 lzmadec, so it is fine to pass also --disable-nls to configure. | |
200 | |
201 - To select somewhat size-optimized variant of some things in | |
202 liblzma, pass --enable-small to configure. | |
203 | |
204 - Tell the compiler to optimize for size instead of speed. | |
205 E.g. with GCC, put -Os into CFLAGS. | |
206 | 151 |
207 | 152 |
208 5. Additional documentation | 153 5. Additional documentation |
209 --------------------------- | 154 --------------------------- |
210 | 155 |
211 "make install" copies some additional documentation to $docdir | 156 "make install" copies some additional documentation to $docdir |
212 (--docdir in configure). These a copy of the GNU GPL v2, which can | 157 (--docdir in configure). There is a copy of the GNU GPL v2, which |
213 be replaced with a symlink if your distro ships with shared copies | 158 can be replaced with a symlink if your distro ships with shared |
214 of the common license texts. | 159 copies of the common license texts. |
| 160 |
| 161 liblzma API is currently only documented using Doxygen tags in the |
| 162 API headers. It hasn't been tested much how good results Doxygen |
| 163 is able to make from the tags (e.g. Doxyfile might need tweaking, |
| 164 the tagging may need to be improved etc.), so it might be simpler |
| 165 to just let people read docs directly from the .h files for now, |
| 166 and also save quite a bit in package size at the same time. |
215 | 167 |
216 | 168 |
217 6. Extra files | 169 6. Extra files |
218 -------------- | 170 -------------- |
219 | 171 |
220 The "extra" directory contains some small extra tools or other files. | 172 The "extra" directory contains some small extra tools or other files. |
221 The exact set of extra files can vary between XZ Utils releases. The | 173 The exact set of extra files can vary between XZ Utils releases. The |
222 extra files have only limited use or they are too dangerous to be | 174 extra files have only limited use or they are too dangerous to be |
223 put directly to $bindir (7z2lzma.sh is a good example, since it can | 175 put directly to $bindir (7z2lzma.sh is a good example, since it can |
224 silently create corrupt output if certain conditions are not met). | 176 silently create corrupt output if certain conditions are not met). |
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239 omitting the compatibility symlinks (lzma, unlzma, lzcat, lzgrep etc.) | 191 omitting the compatibility symlinks (lzma, unlzma, lzcat, lzgrep etc.) |
240 from the XZ Utils package. It's probably a good idea to still package | 192 from the XZ Utils package. It's probably a good idea to still package |
241 the symlinks into a separate package so that users may choose if they | 193 the symlinks into a separate package so that users may choose if they |
242 want to use XZ Utils or LZMA Utils for handling .lzma files. | 194 want to use XZ Utils or LZMA Utils for handling .lzma files. |
243 | 195 |
244 | 196 |
245 8. Example | 197 8. Example |
246 ---------- | 198 ---------- |
247 | 199 |
248 Here is an example for i686 GNU/Linux that | 200 Here is an example for i686 GNU/Linux that |
249 - links xz against static liblzma; | 201 - links xz and lzmainfo against shared liblzma; |
250 - includes only shared liblzma in the final package; | 202 - links size-optimized xzdec and lzmadec against static liblzma |
251 - links xzdec and lzmadec against static liblzma while | 203 while avoiding libpthread dependency; |
252 avoiding libpthread dependency. | 204 - includes only shared liblzma in the final package; and |
| 205 - copies also the "extra" directory to the package. |
253 | 206 |
254 PKG=/tmp/xz-pkg | 207 PKG=/tmp/xz-pkg |
255 tar xf xz-x.y.z.tar.gz | 208 tar xf xz-x.y.z.tar.gz |
256 cd xz-x.y.z | 209 cd xz-x.y.z |
257 ./configure \ | 210 ./configure \ |
258 --prefix=/usr \ | 211 --prefix=/usr \ |
259 --sysconfdir=/etc \ | 212 --disable-static \ |
260 CFLAGS='-march=i686 -O2' | 213 --disable-xzdec \ |
| 214 --disable-lzmadec \ |
| 215 CFLAGS='-march=i686 -mtune=generic -O2' |
261 make | 216 make |
262 make DESTDIR=$PKG install-strip | 217 make DESTDIR=$PKG install-strip |
263 rm -f $PKG/usr/lib/lib*.a | |
264 sed -i "s/^old_library=.*$/old_library=''/" $PKG/usr/lib/lib*.la | |
265 make clean | 218 make clean |
266 ./configure \ | 219 ./configure \ |
267 --prefix=/usr \ | 220 --prefix=/usr \ |
268 --sysconfdir=/etc \ | |
269 --disable-shared \ | 221 --disable-shared \ |
270 --disable-nls \ | 222 --disable-nls \ |
271 --disable-encoders \ | 223 --disable-encoders \ |
272 --enable-small \ | 224 --enable-small \ |
273 --disable-threads \ | 225 --disable-threads \ |
274 CFLAGS='-march=i686 -Os' | 226 CFLAGS='-march=i686 -mtune=generic -Os' |
275 make -C src/liblzma | 227 make -C src/liblzma |
276 make -C src/xzdec | 228 make -C src/xzdec |
277 make -C src/xzdec DESTDIR=$PKG install-strip | 229 make -C src/xzdec DESTDIR=$PKG install-strip |
278 cp -a extra $PKG/usr/share/doc/xz | 230 cp -a extra $PKG/usr/share/doc/xz |
279 | 231 |
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