doc: Add supported distros (kernel, libc, toolchain)

Page put into wiki:
https://github.com/linux-test-project/ltp/wiki/Supported-kernel,-libc,-toolchain-versions

Acked-by: Cyril Hrubis <[email protected]>
Acked-by: Yang Xu <[email protected]>
Acked-by: Jan Stancek <[email protected]>
Acked-by: Li Wang <[email protected]>
Signed-off-by: Petr Vorel <[email protected]>

Author: pevik

doc/supported-kernel-libc-versions.txt

@@ -0,0 +1,66 @@
+Supported kernel, libc, toolchain versions
+==========================================
+
+1. Build testing with Travis CI
+-------------------------------
+
+We test master branch in https://travis-ci.org/github/linux-test-project/ltp/builds[travis CI]
+to ensure LTP builds on various distributions including old, current and bleeding edge.
+We test both gcc and clang toolchains, various architectures with cross-compilation.
+For list of tested distros see
+https://github.com/linux-test-project/ltp/blob/master/.travis.yml[.travis.yml].
+
+
+NOTE: Travis does only build testing, passing the CI means only that the
+      test compiles fine on variety of different distributions and releases.
+      Travis also uses the latest distribution image of a particular release.
+
+1.1 Oldest tested distributions
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+[align="center",options="header"]
+|==============================================================
+| Distro                       | kernel | glibc | gcc   | clang
+| CentOS 7                     | 3.10   | 2.17  | 4.8.5 | -
+| Ubuntu 16.04 LTS xenial      | 4.4    | 2.23  | 5.3.1 | -
+| Debian 9 stretch (oldstable) | 4.9.30 | 2.24  | 6.3.0 | 3.8
+|==============================================================
+
+Older distributions are not officially supported, which means that it
+may or may not work. It all depends on your luck. It should be possible
+to compile latest LTP even on slightly older distributions than we
+support with a few manual tweaks, e.g. disabling manually tests for
+newly added syscalls, etc. Trivial fixes/workarounds may be accepted,
+but users are encouraged to move to a newer distro.
+
+If latest LTP cannot be compiled even with some amount of workarounds,
+you may result to older LTP releases, however these are _not_ supported
+in any way. Also if you are trying to run LTP on more than 10 years old
+distribution you may as well reconsider you life choices.
+
+1.2 Tested architectures
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+[align="center",options="header"]
+|==================================
+| arch          | build
+| x86_64        | native
+| x86 emulation | native
+| aarch64       | cross compilation
+| ppc64le       | cross compilation
+| s390x         | cross compilation
+|==================================
+
+1.3 Supported libc
+~~~~~~~~~~~~~~~~~~
+
+[align="center",options="header"]
+|==================================
+| Libc      | Note
+| https://www.gnu.org/software/libc/[GNU C Library (glibc)] | Targetted libc, tested both compilation and actual test results.
+| https://uclibc-ng.org/[uClibc-ng] | Although not being tested it should work as well as it attempt to maintain a glibc compatible interface.
+| https://www.uclibc.org/[uClibc]   | Older https://www.uclibc.org/[uClibc] might have problems.
+| https://musl.libc.org/[musl] | Not yet fully supported (see
+                                 https://github.com/linux-test-project/ltp/blob/master/travis/alpine.sh[travis script]
+                                 for list of files which need to be deleted in order to compile under musl).
+| binder (Android) | Please use https://android.googlesource.com/platform/external/ltp/[AOSP fork].