gzoned: Introduce Zoned Storage emulator

gzoned(8) is a new GEOM class that exposes a host-managed zoned device
(similar to ZAC/ZBC drives) on top of regular, non-zoned providers.

The created mediu

gzoned: Introduce Zoned Storage emulator

gzoned(8) is a new GEOM class that exposes a host-managed zoned device
(similar to ZAC/ZBC drives) on top of regular, non-zoned providers.

The created medium is sliced into equally sized zones, by default
sequential-write-required. Such zones can be turned into conventional
zones if desired. The zoned drive's state and configuration is
persistent through metadata at the tail of the backing provider, meaning
the zoned device gets recreated at the provider retaste. Zone state
changes only mark the table dirty with BIO_FLUSH committing it,
mirroring drives whose zone state is volatile until a cache flush.

The new class tries to emulate real zoned drives by incorporating
per-zone write pointers and support for BIO_ZONE management commands.
Fault emulation through zone conditions (RWP recommended, offline, R/O),
URSWRZ bit toggling and concurrent open zone limits are additional
features useful for testing.

While at it, fix zonectl's report of write pointer LBAs for zones that
should have none, remove its forced debug flags and allow the geom(8)
shared subroutines to detect host-managed drives.

ATF-sh tests for gzoned(8) and zonectl(8) (dogfooded by gzoned(8)) are
included, featuring helpers (see zoned_subr.sh) for testing zoned
storage support in other components or GEOM classes.

Reviewed by: asomers, fuz, ken
Sponsored by: Google Summer of Code 2026
Pull Request: https://github.com/freebsd/freebsd-src/pull/2326

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Remove residual blank line at start of Makefile

This is a residual of the $FreeBSD$ removal.

MFC After: 3 days (though I'll just run the command on the branches)
Sponsored by: Netflix

Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

geom: Migrate from COMPAT_32BIT to generic COMPAT_libcompat

See commit 8fad2cda93c7 ("bsd.compat.mk: Provide new CPP and sub-make
variables") for the context behind this change.

Reviewed by: imp, b

geom: Migrate from COMPAT_32BIT to generic COMPAT_libcompat

See commit 8fad2cda93c7 ("bsd.compat.mk: Provide new CPP and sub-make
variables") for the context behind this change.

Reviewed by: imp, brooks, jhb
Differential Revision: https://reviews.freebsd.org/D40927

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Create a new GEOM utility, gunion(8).

The gunion(8) utility is used to track changes to a read-only disk on
a writable disk. Logically, a writable disk is placed over a read-only
disk. Write request

Create a new GEOM utility, gunion(8).

The gunion(8) utility is used to track changes to a read-only disk on
a writable disk. Logically, a writable disk is placed over a read-only
disk. Write requests are intercepted and stored on the writable
disk. Read requests are first checked to see if they have been
written on the top (writable disk) and if found are returned. If
they have not been written on the top disk, then they are read from
the lower disk.

The gunion(8) utility can be especially useful if you have a large
disk with a corrupted filesystem that you are unsure of how to
repair. You can use gunion(8) to place another disk over the corrupted
disk and then attempt to repair the filesystem. If the repair fails,
you can revert all the changes in the upper disk and be back to the
unchanged state of the lower disk thus allowing you to try another
approach to repairing it. If the repair is successful you can commit
all the writes recorded on the top disk to the lower disk.

Another use of the gunion(8) utility is to try out upgrades to your
system. Place the upper disk over the disk holding your filesystem
that is to be upgraded and then run the upgrade on it. If it works,
commit it; if it fails, revert the upgrade.

Further details can be found in the gunion(8) manual page.

Reviewed by: Chuck Silvers, kib (earlier version)
tested by: Peter Holm
Differential Revision: https://reviews.freebsd.org/D32697

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Remove GEOM_SCHED class and gsched tool.

This code was not actively maintained since it was introduced 10 years ago.
It lacks support for many later GEOM features, such as direct dispatch,
unmapped

Remove GEOM_SCHED class and gsched tool.

This code was not actively maintained since it was introduced 10 years ago.
It lacks support for many later GEOM features, such as direct dispatch,
unmapped I/O, stripesize/stripeoffset, resize, etc. Plus it is the only
remaining use of GEOM nstart/nend request counters, used there to implement
live insertion/removal, questionable by itself. Plus, as number of people
commented, GEOM is not the best place for I/O scheduler, since it has
limited information about layers both above and below it, required for
efficient scheduling. Plus with the modern shift to SSDs there is just no
more significant need for this kind of scheduling.

Approved by: imp, phk, luigi
Relnotes: yes

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Add a file missed in r335645.

Approved by: brooks, allanjude (mentor)
Differential Revision: https://reviews.freebsd.org/D15360