libuvmem: usermode port of vmem(9)

[kib]

Summary

The quantum cache is disabled, there is no uma.

Intent is to use this for resource allocation in bhyve(8), for start. Addition of -luvmem to bhyve linking was done to test changes to share/mk.

[grehan]

No objection from bhyve's PoV.

[markj]

Seems ok to me, just nitpicking.

sys/kern/subr_vmem.c

609

Commit separately?

817

I would delete the rehash comment and merge the two blocks. All of the functions below can arguably be called "vmem internal functions".

823

This can be a separate commit.

853–854

This can be a separate commit.

1367

Why?

1461

I really dislike conditionally defined top-level local variables, so I'd prefer to move the definition into the if block below. I don't insist on it though.

1594

You could eliminate some inline ifdefs with #define panic(...) assert(0).

1602–1603

Same comment as above wrt local variables.

1618

This can be a separate commit.

1714

This block should probably be formally protected with ifdef _KERNEL as well.

[emaste]

sys/kern/subr_vmem.c

1461

I agree in general, and if this were some special case (e.g. INVARIANTS) instead of the usual case I'd argue strongly for markj's take.

[kib]

sys/kern/subr_vmem.c

1367

To not add __unused declaration, I think it is logically wrong.

1594

There were only two of them so I did not bothered.

[kib]

Rebase after commit of warning fixes.
Handle Mark notes.

[markj]

sys/contrib/openzfs/include/sys/zfs_context.h

53

Is this just a reminder to upstream the change? Or is there another problem?

sys/kern/subr_vmem.c

1367

I think (void)qcache_max; is more common for this scenario.

[kib]

Add M_*FIT bits to sys/vmem.h for userspace.