[PATCH] Deprecate Unicore32 port

[Peter Maydell]

Deprecate our Unicore32 target support:
 * the Linux kernel dropped support for unicore32 in commit
   05119217a9bd199c for its 5.9 release (with rationale in the
   cover letter: https://lkml.org/lkml/2020/8/3/232 )
 * there is apparently no upstream toolchain that can create unicore32
   binaries
 * the maintainer doesn't seem to have made any contributions to
   QEMU since the port first landed in 2012
 * nobody else seems to have made changes to the unicore code except
   for generic cleanups either

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
We last considered this back in 2018, but in the end both QEMU
and the kernel gave the port a stay of execution; the maintenance
situation doesn't seem to have improved, and now the kernel has
dropped support and especially given the lack of a toolchain
I think it's time to start the deprecation process here.
---
 docs/system/deprecated.rst | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index 851dbdeb8ab..4c52098c707 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -416,6 +416,14 @@ The above, converted to the current supported format::
 linux-user mode CPUs
 --------------------
 
+``unicore32`` CPUs (since 5.2.0)
+''''''''''''''''''''''''''''''''
+
+The ``unicore32`` guest CPU support is deprecated and will be removed in
+a future version of QEMU. Support for this CPU was removed from the
+upstream Linux kernel, and there is no available upstream toolchain
+to build binaries for it.
+
 ``tilegx`` CPUs (since 5.1.0)
 '''''''''''''''''''''''''''''
 
-- 
2.20.1