[Qemu-devel] Proposal: deprecate and remove QEMU's unicore32 target code

[Peter Maydell]

I propose that we deprecate and plan to remove the unicore32 code:

 * It has had no changes since 2012 that were not tree-wide
   maintenance/API changes/other global updates
 * We dropped the linux-user unicore32 support in 2016 because of
   a clash between the 'old ABI' that it was implementing and the
   ABI that's actually in the upstream Linux kernel, and there have
   been no moves to get this fixed so we could re-enable it, nor
   any complaints when it went away
 * Linux is now planning to drop unicore support
   (https://www.mail-archive.com/address@hidden/msg1619640.html)
 * there is apparently no upstream gcc support for the architecture
 * nobody has ever reported a bug or problem to us about it

Essentially, it seems to be a largely-inactive university R&D project,
it's costing us in maintenance effort every time we have to touch it,
and I don't think it has any real users.

Does anybody disagree?

If we go ahead with deprecating then we should:
 * add a note to Changelog that we're deprecating the target
 * ditto qemu-doc.texi's deprecation section
 * patch hw/unicore32/puv3.c to warn on startup that it's deprecated
 * remove it entirely for the 2.14 release

We could also remove linux-user/unicore32 immediately, since
the linux-user target has been disabled for some time.

Possibly there are other target architectures we could reasonably
deprecate-and-remove (though none of the other ones Linux is dropping
in this round are ones we support)...

thanks
-- PMM