risc-v: add support for PCI and the PCIe controller in the JH7110 SoC.

Testing as working with xhci and nvme on VisionFive2.

Uses legacy PCI interrupts currently. MSIs to be added later.

pcihost_fdt code is 99% the same as the Arm version and should be shared.

risc-v: split db_{read,write}_bytes from db_machdep.c

Another step towards crash(8) support

branches: 1.15.2;
Provide and use _ucas_{32,64} implementations

Fix and enable MULTIPROCESSOR

risc-v: MULTIPROCESSOR support

Add MULTIPROCESSOR support for RISC-V, but leave disabled for the moment
as it's not 100% stable.

Some other improvements to spl and cpu identification / reporting.

RISC-V support that works on QEMU with a single hart.

Thanks for Simon Burge for plic(4).

Split out a bunch of functions from locore.S into cpu_switch.S

NFC

Basic ddb and backtrace support.

[ 1.0000000] panic: kernel diagnostic assertion "msgbufaddr != 0" failed: file "/home/nick/netbsd/nbcvs/src/sys/arch/riscv/riscv/riscv_machdep.c", line 564
[ 1.0000000] cpu0: Begin traceback...
[ 1.0000000] trace fp ffffffc000801dd0
[ 1.0000000] fp ffffffc000801e10 ?() at ffffffc0001eee98
[ 1.0000000] fp ffffffc000801e30 ?() at ffffffc0002ad984
[ 1.0000000] fp ffffffc000801ee0 ?() at ffffffc000005430
[ 1.0000000] cpu0: End traceback...
[ 1.0000000] Trapframe @ 0xffffffc000801cb0 (cause=3 (breakpoint), status=0x100, pc=0xffffffc0000007e4, va=0):
[ 1.0000000] ra =0xffffffc0001eee9c, sp =0xffffffc000801dd0, gp =0xffffffc0006a8f40, tp = 0
[ 1.0000000] s0 =0xffffffc000600ac0, s1 = 0x1000, s2 =0xffffffc000438df0, s3 =0xffffffc000801d80
[ 1.0000000] s4 =0xffffffc0001eed78, s5 =0xffffffc0006d55f8, s6 =0xffffffc000801d88, s7 =0xffffffc0006dfdb8
[ 1.0000000] s8 =0xffffffc000428c18, s9 =0xffffffc000801dd0, s10=0xffffffc0000a3822, s11=0xffffffc0006d55f8
[ 1.0000000] a0 = 0x17, a1 = 0xa, a2 = 0, a3 =0xffffffc00041f658
[ 1.0000000] a4 = 0, a5 = 0x1, a5 = 0, a7 = 0x1
[ 1.0000000] t0 =0xffffffc0006dfe30, t1 =0xffffffc000801bb8, t2 =0xffffffc000803000, t3 = 0x75
[ 1.0000000] t4 = 0, t5 = 0x63, t6 = 0x1
[ 1.0000000] kernel: breakpoint
Stopped in pid 0.0 (system) at ffffffc0000007e4: c.ebreak
db>

Sort. NFC.

Add some bus_space(9), bus_dma(9) and FDT infrastructure. Baby steps.

Remove the RISC-V Host Target Interface (HTIF) Emulation code.

Miscellaneous updates to reflect riscv-privileged-20190608.pdf

Some from zmcgrew@

branches: 1.6.2;
make process_machdep.c included always since it provides register i/o used by
sys_process_getlwpstatus.c which is always included.

harmonize process_machdep.c inclusion.

Move all non-emulation-specific coredump code into the coredump module,
and remove all #ifdef COREDUMP conditional compilation. Now, the
coredump module is completely separated from the emulation modules, and
they can all be independently loaded and unloaded.

Welcome to 9.99.18 !

Misc changes in RISC-V.

Misc changes in RISC-V. Start changing the memory layout, too.

branches: 1.1.2; 1.1.18; 1.1.22;
Beginnings of RISCV kernel support. Note that the pmap support is not yet
committed and probably won't be for awhile. This is mostly preliminary
waiting for the supervisor specification to come out. Lots of missing pieces
but it mostly builds.