MFC r330004: Add NO_OBJ to those directories that don't make anything.

For directories that don't many anything, add NO_OBJ=t just before we
include bsd.init.mk. This prevents them from creating an OBJ
directory. In addition, prevent defs.mk from creating the machine
related links in these cases. They aren't needed and break, at least
on stable, the read-only src tree build.

PR: 226074

MFC r325834,r325997,326502: Move sys/boot to stand/

This is effectively a direct commit to stable/11, due to differences between
stable/11 and head. Changes to DTS in sys/boot/fdt/dts were often
accompanied by kernel changes. Many of these were also risc-v updates that
likely had many more dependencies to MFC.

Because of this, sys/boot/fdt/dts remains as-is while everything else in
sys/boot relocates to stand/.

r325834: Move sys/boot to stand. Fix all references to new location

r325997: Remove empty directories.

r326502: Document the sys/boot -> stand move in hier.7 and the top-level README.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

This review aims at introducing ubldr (loader with U-Boot interface) for MIPS
(32 and 64-bit, LE and BE).
The changes were tested with QEMU's 'mips' target.

Most of the implementation was lifted from the ARM version, the appropriate
MIPS-specific things were implemented.

With these changes I am able to go all the way through the u-boot->ubldr->kernel
boot chain in QEMU on all combinations of bit-ness and endian-ness.

For the tests I've used FAT32 disk images (as FAT32 is supported by U-boot),
which include /boot/kernel/kernel and /boot/kernel/ubldr.bin

In U-boot I do:
fatload ide 0 <LOAD_ADDR> /boot/kernel/ubldr.bin; go <LOAD_ADDR>
where LOAD_ADDR is 80800000 for 32-bit and ffffffff80800000 for 64-bit

Then it's the usual ubldr that takes over and loads and starts a kernel.

Approved by: adrian (mentor)
Sponsored by: Smartcom - Bulgaria AD
Differential Revision: https://reviews.freebsd.org/D5313

Build the BERI boot loader on 64-bit MIPS (but not 32-bit MIPS). While
these binaries aren't immediately useful on other MIPSes, still build them
as part of mips64 world in order to expose them to tinderbox.

MFC after: 3 weeks
Sponsored by: DARPA, AFRL

Temporarily unhook BERI boot loader from the build until 32-bit MIPS
properly excludes building our 64-bit only boot-loader adaptation.

Commit a first cut at ports of boot2 and loader to 64-bit MIPS, with a
particular interest in (and support for) SRI International and the
University of Cambridge's BERI FPGA soft-core processor. This includes
micro device drivers for the Altera JTAG UART console, memory-mapped
flash, and the Altera SD Card IP core in both boot2 and loader. boot2
can be written to the on-board Intel StrataFlash on the DE4 board, and
loader can be placed in StrataFlash or the SD Card.

Plenty of XXX comments, but works quite well locally in practice and I
am using it daily. Although I had originally ported the ARM version
of boot2, the current version is x86-derived as that proved more
feature-complete. As we don't currently use partitions on our flash
disks, support for that has been commented out relative to x86, but
would be easy to add back. FDT support has not yet been hooked up,
although some skeleton parts have been put in place for that.

This may well be a useful starting point for ports to other 32-bit and
64-bit MIPS-ISA systems.

This merge is synchronised to CheriBSD github commit
e41d74fd719525d4dd7a7ee499114679165eeaf6, but with some additions of
$FreeBSD.

MFC after: 3 weeks
Sponsored by: DARPA, AFRAL