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.

MFC r303555,r303556,r303936,r303962,r304317,r304532,r305026,r305107,r305132,
r305178,r305353,r305814,r306159,r306380,r306504: Loader fixes, 2016q3

r303555: bcache should support reads shorter than sector size

r303556: Improve boot loader quote parsing

r303936: Add kernel environment variables under smbios.system

r303962: Add the missing space between .asciz directive and opening quote
for some lines with #ifdef BTXLDR_VERBOSE/#endif

r304317: boot1.efi Free() should check for NULL to provide consistent
behavior

r304532: Replace sprintf -> snprintf for command_errbuf provisioned from
dynamic content.

r305026: Emulate efi_cons_poll when WaitForKey is not available

r305107: Create a hook 'post-initialize' for people that want to define
something to read in .conf files after all other .conf files for the purpose
of overriding.

r305132: Remove accidentally committed stray comment.

r305178: bd_int13probe() should check extended info if sector info is bad

r305353: Don't use -N to set the OMAGIC with data and text writeable and
data not page aligned.

r305814: ufsread: Do not cast struct direct from void *

r306159: Consistently declare getsecs(void) with proper return type and void
when no arguments are present.

r306380: loader command interpreter should reset command_errmsg

r306504: Fix a cluster of bugs in list EFI environment variables

PR: 204602, 211958, 211958
Relnotes: yes ("Improve boot loader quote parsing")

MFC r310702: btxldr: process all PT_LOAD segments, not just the first two

With default settings GNU ld generates two PT_LOADs for loader.sym while
LLD generates three, because it creates a rodata segment. Previously
btxldr terminated phdr processing after two PT_LOADs. Remove the early
termination to process all PT_LOADs.

Sponsored by: The FreeBSD Foundation

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

btxldr: future-proof argument passing from boot1/2-ish to loader

Place the arguments at a fixed offset of 0x800 withing the argument area
(of size 0x1000). Allow variable size extended arguments first of which
should be a size of the extended arguments (including the size
parameter).

Consolidate all related definitions in a new i386/common/bootargs.h header.

Many thanks to jhb and bde for their guidance and reviews.

Reviewed by: jhb, bde
Approved by: jhb
MFC after: 1 month

Remove now unused label.

Submitted by: Christoph Mallon
MFC after: 4 weeks
(along with r185779 and r185780)

Optimiza assembly in the previous r185779, to save whooping 16 bytes.

Submitted by: Christoph Mallon
MFC after: 4 weeks
(including r185779)

Respect RBX_MUTE flag from boot[012].

MFC after: 4 weeks

Back out last revision that unnecessarily changed valid assembler
line comments and damaged the CVS history.

Prompted by: bde, jhb

After talking to Bruce Evans and reading more standards specs,
switch to using C99-style comments everywhere in preprocessed
assembler. The reason is that lines starting with the regexp
'^[[:space:]]#' are treated as preprocessing directives, and
while it seems to work now with GCC, it's not necessarily has
to work. Use C99 comments `//' for the trailing comments to
save whitespace.

Use C (and CPP) style comments for assembler-with-cpp sources,
for lines that start with a comment.

Get rid of unnecessary use of m4(1) by using cpp(1) instead.
(John tells me there were problems when trying this before,
but it appears to be safe these day.)

OK'ed by: jhb
Repocopied by: joe

Fix an incorrect quote character in an M4 test conditon. Basically, one
of the verbose print statements that BTXLDR_VERBOSE enables wasn't properly
enabled.

Revert MEM_USR back to 0xa000 for BTX clients. Instead, adjust boot2
to run at 0xc000 by changing its virtual start address from 0x1000 to
0x2000.

Tested by: phk

Correctly adjust for moved start address.

It seems that the existence of a "depend" target in src/sys/boot is not
to be taken as an indication that it actually does what one would expect,
at least it clearly threw my testing off.

Apologies to: jhb

Convert the short stub of real-mode code into 16-bit assembly.

Mega i386 loader commit.
- Don't hard code 0x10000 as the entry point for the loader. Instead add
src/sys/boot/i386/Makefile.inc which defines a make variable with the
entry point for the loader. Move the loader's entry point up to
0x20000, which makes PXE happy.
- Don't try to use cpp to parse btxldr for the optional BTXLDR_VERBOSE,
instead use m4 to achieve this. Also, add a BTXLDR_VERBOSE knob in the
btxldr Makefile to turn this option on.
- Redo parts of cdldr's Makefile so that it now builds and installs cdboot
instead of having i386/loader/Makefile do that. Also, add in some more
variables to make the pxeldr Makefile almost identical and thus to ease
maintainability.
- Teach cdldr about the a.out format. Cdldr now parsers the a.out header
of the loader binary and relocates it based on that. The entry point of
the loader no longer has to be hardcoded into cdldr. Also, the boot
info table from mkisofs is no longer required to get a useful cdboot.
- Update the lsdev function for BIOS disks to parse other file systems
(such as DOS FAT) that we currently support. This is still buggy as
it assumes that a floppy with a DOS boot sector actually has a MBR and
parses it as such. I'll be fixing this in the future.
- The biggie: Add in support for booting off of PXE-enabled network
adapters. Currently, we use the TFTP API provided by the PXE BIOS.
Eventually we will switch to using the low-level NIC driver thus
allowing both TFTP and NFS to be used, but for now it's just TFTP.

Submitted by: ps, alfred
Testing by: Benno Rice <benno@netizen.com.au>

Add the new cdldr CD bootstrap loader. This patch includes the following:

- Fix btxldr to preserve a NULL bootinfo pointer when it copies the kernel
arguments.
- Add the cdldr bootstrap program. This program is tacked onto the
beginning of the standard 3rd stage boot loader (/boot/loader) to form
the CD boot loader (/boot/cdboot). When a CD is booted, the cdboot file
is copied into memory instead and executed. The cdldr stub emulates the
environment normally provided by boot2 and then starts the loader. This
booting method does not emulate a floppy drive, but boots directly off of
the CD. This should fix the problems some BIOS's have with emulating a
2.88 MB floppy image.
- Add support to the loader to recognize that it has been booted by cdldr
instead of boot2 and use a simpler method of extracting the BIOS boot
device.

Blank out the twiddly thing when outputting the ``BTX loader'' message.

$Id$ -> $FreeBSD$

Push version numbers up to 1.00. This is just intended to reflect
that the BTX code can be regarded as stable: there are no associated
code changes.

Suggested by: obrien

Make the BTX loader much more quiet about what it's doing. This removes
most of the "what the (*^&%(*^ was that?" stuff that normally flies by.

Fix for "get base memory" bug found and mostly fixed by Mike.

The BIOS memory size is only a word. Some BIOSsen have garbage in the other
16 bits we were reading here, causing loss of arguments.

Add btxldr, a BTX loader for ELF clients.