|
|
@@ -1,20 +1,62 @@
|
|
|
Building Dinit
|
|
|
=-=-=-=-=-=-=-
|
|
|
|
|
|
-Buildingn Dinit should be a straight-forward process. It requires GNU make.
|
|
|
+Building Dinit should be a straight-forward process. It requires GNU make.
|
|
|
|
|
|
Edit the "mconfig" file to choose appropriate values for the configuration variables defined
|
|
|
within. In particular:
|
|
|
|
|
|
CXX : should be set to the name of the C++ compiler (and linker)
|
|
|
- CXXOPTS : are options passed to the compiler during compilation
|
|
|
+ CXXOPTS : are options passed to the compiler during compilation (see note for GCC below)
|
|
|
EXTRA_LIBS : are any extra libraries required for linking; should not normally be needed.
|
|
|
|
|
|
-Defaults for Linux and OpenBSD are provided. Note that the "eg++" package must be installed
|
|
|
-on OpenBSD as the default "g++" compiler is too old.
|
|
|
+Defaults for Linux and OpenBSD are provided. Note that the "eg++" or "clang++" package must
|
|
|
+be installed on OpenBSD as the default "g++" compiler is too old. Clang is part of the base
|
|
|
+system in recent releases.
|
|
|
|
|
|
Then, change into the "src" directory, and run "make" (or "gmake" if the system make is not
|
|
|
-GNU make):
|
|
|
+GNU make, such as on most BSD systems):
|
|
|
|
|
|
cd src
|
|
|
make
|
|
|
+
|
|
|
+If everything goes smoothly this will build dinit, dinitctl, and optionally the shutdown
|
|
|
+utility. Use "make install" to install; you can specify an alternate installation by
|
|
|
+setting the "DESTDIR" variable, eg "make DESTDIR=/tmp/temporary-install-path install".
|
|
|
+
|
|
|
+
|
|
|
+Special note for GCC/Libstdc++
|
|
|
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
|
|
|
+
|
|
|
+GCC 5.x onwards includes a "dual ABI" in its standard library implementation, aka Libstdc++.
|
|
|
+Compiling against the newer (C++11 and later) ABI can be achieved by adding
|
|
|
+-D_GLIBCXX_USE_CXX11_ABI=1 to the compiler command line; this uses a non-standard language
|
|
|
+extension to differently mangle symbol names in order to link against the new ABI versions.
|
|
|
+
|
|
|
+(Some systems may be configured to build with the new ABI by default, and in that case you
|
|
|
+build against the old ABI using D_GLIBCXX_USE_CXX11_ABI=1).
|
|
|
+
|
|
|
+This is problematic for several reasons. First, it prevents linking against the new ABI with
|
|
|
+other compilers that do not understand the language extension (LLVM i.e. clang++ does so
|
|
|
+in recent versions, so this is perhaps no longer much of a problem in practice). Secondly,
|
|
|
+some aspects of library behavior are ABI-dependent but cannot be changed using the ABI
|
|
|
+macro; in particular, exceptions thrown as a result of failed I/O operations are, in GCC
|
|
|
+versions 5.x and 6.x, always "old ABI" exceptions which cannot be caught by code compiled
|
|
|
+against the new ABI, and in GCC version 7.x they are always "new ABI" exceptions which cannot
|
|
|
+be caught by code compiled against the old ABI. Since the one library object now supposedly
|
|
|
+houses both ABIs, this means that at least one of the two ABIs is always broken.
|
|
|
+
|
|
|
+A blog post describing the dual ABI mechanism can be found here:
|
|
|
+
|
|
|
+ https://developers.redhat.com/blog/2015/02/05/gcc5-and-the-c11-abi/
|
|
|
+
|
|
|
+The bug regarding the issue with catching other-ABI exceptions is here:
|
|
|
+
|
|
|
+ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66145
|
|
|
+
|
|
|
+Since Dinit is affected by this bug, the unfortunate possibility exists to break Dinit by
|
|
|
+upgrading GCC. If you have libstdc++ corresponding to GCC 5.x or 6.x, you *must* build with
|
|
|
+the old ABI, but Dinit will be broken if you upgrade to GCC 7. If you have libstdc++ from
|
|
|
+GCC 7, you *must* build with the new ABI. If the wrong ABI is used, Dinit may still run
|
|
|
+successfully but any attempt to load a non-existing service, for example, will cause Dinit
|
|
|
+to crash.
|
Davin McCall