Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20210718' into staging

target-arm queue:
 * Remove duplicate 'plus1' function from Neon and SVE decode
 * Fix offsets for TTBCR for big-endian hosts
 * docs: fix copyright date
 * docs: add license/version info to HTML footers
 * docs: add an About section
 * docs: document some more arm boards

# gpg: Signature made Sun 18 Jul 2021 13:45:22 BST
# gpg:                using RSA key E1A5C593CD419DE28E8315CF3C2525ED14360CDE
# gpg:                issuer "peter.maydell@linaro.org"
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>" [ultimate]
# gpg:                 aka "Peter Maydell <pmaydell@gmail.com>" [ultimate]
# gpg:                 aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>" [ultimate]
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83  15CF 3C25 25ED 1436 0CDE

* remotes/pmaydell/tags/pull-target-arm-20210718:
  target/arm: Remove duplicate 'plus1' function from Neon and SVE decode
  docs: Add skeletal documentation of highbank and midway
  docs: Add skeletal documentation of the emcraft-sf2
  docs: Add skeletal documentation of cubieboard
  docs: Add QEMU version information to HTML footer
  docs: Add license note to the HTML page footer
  docs: Add some actual About text to about/index.rst
  docs: Move deprecation, build and license info out of system/
  docs: Remove "Contents:" lines from top-level subsections
  docs: Stop calling the top level subsections of our manual 'manuals'
  docs: Fix documentation Copyright date
  target/arm: Fix offsets for TTBCR

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 62 insertions, 0 deletions

diff --git a/docs/about/build-platforms.rst b/docs/about/build-platforms.rst
new file mode 100644
index 0000000000..692323609e
--- /dev/null
+++ b/docs/about/build-platforms.rst
@@ -0,0 +1,62 @@
+.. _Supported-build-platforms:
+
+Supported build platforms
+=========================
+
+QEMU aims to support building and executing on multiple host OS
+platforms. This appendix outlines which platforms are the major build
+targets. These platforms are used as the basis for deciding upon the
+minimum required versions of 3rd party software QEMU depends on. The
+supported platforms are the targets for automated testing performed by
+the project when patches are submitted for review, and tested before and
+after merge.
+
+If a platform is not listed here, it does not imply that QEMU won't
+work. If an unlisted platform has comparable software versions to a
+listed platform, there is every expectation that it will work. Bug
+reports are welcome for problems encountered on unlisted platforms
+unless they are clearly older vintage than what is described here.
+
+Note that when considering software versions shipped in distros as
+support targets, QEMU considers only the version number, and assumes the
+features in that distro match the upstream release with the same
+version. In other words, if a distro backports extra features to the
+software in their distro, QEMU upstream code will not add explicit
+support for those backports, unless the feature is auto-detectable in a
+manner that works for the upstream releases too.
+
+The `Repology`_ site is a useful resource to identify
+currently shipped versions of software in various operating systems,
+though it does not cover all distros listed below.
+
+Linux OS, macOS, FreeBSD, NetBSD, OpenBSD
+-----------------------------------------
+
+The project aims to support the most recent major version at all times. Support
+for the previous major version will be dropped 2 years after the new major
+version is released or when the vendor itself drops support, whichever comes
+first. In this context, third-party efforts to extend the lifetime of a distro
+are not considered, even when they are endorsed by the vendor (eg. Debian LTS).
+
+For the purposes of identifying supported software versions available on Linux,
+the project will look at CentOS, Debian, Fedora, openSUSE, RHEL, SLES and
+Ubuntu LTS. Other distros will be assumed to ship similar software versions.
+
+For FreeBSD and OpenBSD, decisions will be made based on the contents of the
+respective ports repository, while NetBSD will use the pkgsrc repository.
+
+For macOS, `HomeBrew`_ will be used, although `MacPorts`_ is expected to carry
+similar versions.
+
+Windows
+-------
+
+The project supports building with current versions of the MinGW toolchain,
+hosted on Linux (Debian/Fedora).
+
+The version of the Windows API that's currently targeted is Vista / Server
+2008.
+
+.. _HomeBrew: https://brew.sh/
+.. _MacPorts: https://www.macports.org/
+.. _Repology: https://repology.org/