## General |
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Generally CppCMS can be used as-is for embedded systems. However there are many features that are heavy and targeted |
for high performance web servers. These options |
are rather useless for embedded system. |
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Thus additional build options that make this library optimized for embedded system provided. |
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They are reduce number of dependencies and make executable |
significantly smaller. |
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## Changes in Embedded Build |
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### Normal Embedded Build |
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- Caching is completely removed. Small memory footprint |
is very important for embedded system thus, caching |
stuff in memory is quite useless. |
- Zlib compression are removed -- it removes dependency on `boost::iostreams`, zlib and bzip2 libraries. |
- Removed mod-prefork. |
- Removed dynamic templates loading --- this feature requires export of symbols to binary and increases its size in order to make RTTI work. Thus, all templates should be |
statically compiled into the binary. |
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### CGI Mode |
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- FastCGI and SCGI APIs are removed |
- Mod-thread and mod process are removed including |
all thread pool facilities |
- Changes in files based session backend to work |
properly with CGI mode including garbage collection |
(sessions that had time-out). |
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### Minimal Dependencies |
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Embedded compilation allows building CppCMS using only following libraries: |
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- libcgicc |
- libboost\_signals |
- libboost\_regex. |
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## Cross Compilation of CppCMS |
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### General |
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For cross compilation you should use `--host` configuration switch according to your platform, for example: |
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./configure --host=arm-linux-eabi ... |
./configure --host=mips-linux-gnu |
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Do not forget to build boost and cgicc as well. Refer to |
your platform documentation for cross-compilation instructions. |
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### Build Flags: |
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- `--enable-embedded` -- Create embedded version of cppcms. |
- `--enable-cgi` -- implement CGI API only. |
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_Additional flags:_ |
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- `CXXFLAGS=-Os` -- optimize for size when you build |
for embedded system |
- `--prefix=/...` -- always specify installation prefix... You do not want to install to `/usr/local/lib`, `;-)` |
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For example: |
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./configure --host=arm-linux-gnu --prefix=/usr/arm-linux-gnu CXXFLAGS=-Os --enable-embedded --enable-cgi |
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Would configure cross compilation make files for ARM platform, |
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_Notes:_ |
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- Remember that you should build cgicc and boost as well |
- It is recommended to build `boost::regex` without ICU support in order to reduce executable size. |
- Use `strip --strip-all` to reduce your executable size. |
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## Static Linking |
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In some cases you want to build your application |
without dependencies on many shared objects. |
Thus you can link your application "almost" statically. |
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Only system libraries like libc, libstdc++, pthreads, rt would be linked dynamically |
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### CGI Only |
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You can build "almost" static build as following: |
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g++ hello.o /path/to/libcppcms.a /path/to/libcppcmstranstext.a /path/to/libboost_signals.a /path/to/libboost_regex.a /path/to/libcgicc.a |
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### With Worker Threads |
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You can build "almost" static build as following: |
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g++ hello.o /path/to/libcppcms.a /path/to/libcppcmstranstext.a /path/to/libboost_signals.a /path/to/libboost_regex.a /path/to/libcgicc.a -lrt -lpthread |
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