Re: Future of armv7

Hello John,

Am Fri, Nov 14, 2025 at 12:09:07PM -0500 schrieb John Baldwin:
> Two and a half years ago when we first began talking about deprecating
> 32-bit architectures in 15.0, we decided to keep armv7 for at least
> the stable/15 branch but did not commit to anything beyond that.  Now
> that 15.0 is close to shipping and we are turning our development
> focus to 16.0, we should figure out what we want to say about armv7
> for 16.x in the 15.0 release notes so that users have suitable notice.
> 
> In particular, do we want to deprecate armv7 in 16.0 (similar to the
> state of 32-bit powerpc in 15.0), or do we want to keep it?
> 
> My initial suggestion is that we announce that we plan to deprecate it
> in 16.0.  In that case, I would also suggest that we follow a similar
> process of keeping armv7 for most of the lifetime of 16.0 so that we
> can reneg if need be during the 16.0 cycle.
> 
> What do other folks think?

I do think armv7 is valuable to have in the kernel for two reasons:

 - there are quite a few embedded boards without aarch64 support that
   enjoy use in contexts where FreeBSD is of use, such as in IoT
   devices.

 - the presence of at least one 32 bit platform ensures our kernel is
   compatible with 32 bit platforms, which is in particular useful for
   downstream consumers such as RTEMS that build upon our kernel or
   parts of it and might still want to support 32 bit platforms.  For
   the same reason, we should strive to support at least one BE platform.

That said, I strongly recommend that armv7 world be supported
indefinitely via freebsd32 support on aarch64 (that is, through lib32
or through an armv7 jail on an aarch64 host).  My main use case is
taking embedded microcontroller code and testing it on hosted platforms
by stubbing out the HW access bits with system calls.  This is a very
convenient development process that works through armv7-a being largely
a superset of armv7-m.

As for personal commitment, I plan to continue my effort on QA for ports
on armv7 and to fix any kernel or userland bugs encountered through this
effort.

Yours,
Robert Clausecker

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