Re: FreeBSD mips support

On 9/23/21 1:01 PM, Warner Losh wrote:
> Greetings,
> 
> I think it may be about time to remove MIPS support from the tree. The last
> major users have moved on, and the port suffers from a number of problems
> on modern systems with modern workloads. We have a number of workarounds in
> the tree for different aspects of the mips port that we could retire as
> well...
> 
> I'd like to propose removal of mips from -current soon, say by the end of
> the year.
> 
> Comments?

I can confirm that the CHERI folks at Cambridge have moved all of their
work off of MIPS and onto RISC-V and Morello (aarch64).  I don't foresee
anyone from the CHERI team providing future support for either FreeBSD/mips
or the LLVM MIPS backend.

I can say that based on my recent experience, the MIPS kernel port is a bit
hackish relative to some of our other architecture ports.  The pmap is
missing proper support for resolving virtual aliases which prevents the use
of unmapped I/O.  The n32 kernel support is rather odd and should probably
be axed.  n32 support should really only be as a user ABI via a
COMPAT_FREEBSDN32 or the like, but I don't foresee anyone working on that.
The kernel stack is rather tight (and not easily changed in size).

-- 
John Baldwin