Add COMPAT_FREEBSD11 and use it vm_meter.c.

[markj]

Summary

COMPAT_FREEBSD11 was added to all configs containing COMPAT_FREEBSD10.

The vm_meter.c change will be committed separately.

[rstone]

sys/vm/vm_meter.c

318 ↗

(On Diff #22768)

should this be if defined(COMPAT_FREEBSD11) || defined(COMPAT_FREEBSD10) ...?

I'm not sure if anybody would intentionally have COMPAT_FREEBSD10 but not COMPAT_FREEBSD11, so this may be a rather hypothetical concern.

[markj]

sys/vm/vm_meter.c

318 ↗

(On Diff #22768)

There's always an implicit dependency of COMPAT_FREEBSD<n> on COMPAT_FREEBSD<n+1>, though in this case there's obviously no actual dependency. It'd be nice if config(8) automatically handled this, but until then I'd rather just leave it as-is.

[jhb]

Looks fine to me. I have a slight preference for doing COMPAT_FREEBSD11 in a separate commit from its first use.

sys/vm/vm_meter.c

318 ↗

(On Diff #22768)

Mark is correct, the various compat options all require any "newer" compat options as well. Some of the #ifdef's would be very verbose otherwise. Right now we key the #ifdef off the first version it is removed (and put it under <n>). We'd have to instead figure out the range of used versions each time instead (and in this case this one would go all the way back for example).

One way we could perhaps make this explicit (but it would be a bit of work), would be to use a single COMPAT_FREEBSD option which is assigned a value of the oldest major version, so e.g.:

options  COMPAT_FREEBSD=9   # Support for binaries from 9.0 and later

This would still make the same assumption we make now, but instead of having to add a new COMPAT_FREEBSD<n> and updating kernel configs all the time, one just uses

#if COMPAT_FREEBSD <= 10
/* stub for something removed in 11 */
#endif

It also prevents users from generating an invalid kernel config.