MFH: r309295

bhyve: stability and performance improvement for dbgport

The TCP server implementation in dbgport does not track clients, so it
may try to write to a disconected socket resulting in SIGPIPE.
Avoid that by setting SO_NOSIGPIPE socket option.

Because dbgport emulates an I/O port to guest, the communication is done
byte by byte. Reduce latency of the TCP/IP transfers by using
TCP_NODELAY option. In my tests that change improves performance of
kgdb commands with lots of output (e.g. info threads) by two orders of
magnitude.

A general note. Since we have a uart emulation in bhyve, that can be
used for the console and gdb access to guests. So, bvmconsole and bvmdebug
could be de-orbited now. But there are many existing deployments that
still dependend on those.

Discussed with: julian, jhb
Sponsored by: Panzura

MFH: r307917

accept4 actually expect SOCK_NONBLOCK and not O_NONBLOCK

Reported by: jhb
Pointyhat to: bapt

MFH: r306554

Use accept4 with O_NONBLOCK rather than accept + fcntl

MFC r284539, r284630, r284688, r284877, r285217, r285218,
r286837, r286838, r288470, r288522, r288524, r288826,
r289001

Pull in bhyve bug fixes and changes to allow UEFI booting.
This provides Windows support.

Tested on Intel and AMD with:
- Arch Linux i386+amd64 (kernel 4.3.3)
- Ubuntu 15.10 server 64-bit
- FreeBSD-CURRENT/amd64 20160127 snap
- FreeBSD 10.2 i386+amd64
- OpenBSD 5.8 i386+amd64
- SmartOS latest
- Windows 10 build 1511'

Huge thanks to Yamagi Burmeister who submitted the patch
and did the majority of the testing.

r284539 - bootrom mem allocation support
r284630 - Add SO_REUSEADDR when starting debug port
r284688 - Fix a regression in "movs" emulation
r284877 - verify_gla() non-zero segment base fix
r285217 - Always assert DCD and DSR in the uart
r285218 - devmem nodes moved to /dev/vmm.io/
r286837 - Add define for SATA Check-Power-Mode
r286838 - Add simple (no-op) SATA cmd emulations
r288470 - Increase virtio-blk indirect descs
r288522 - Firmware guest query interface
r288524 - Fix post-test typo
r288826 - Clean up SATA unimplemented cmd msg
r289001 - Add -l option to specify userboot path

Submitted by: Yamagi Burmeister
Approved by: re (kib)

MFC 261607:
Mark the I/O ports used by the bhyve console and debug devices as system
resources.

MFC 261607:
Mark the I/O ports used by the bhyve console and debug devices as system
resources.