NetBSD/arc 9.0

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

NetBSD/arc has been broken since matt-nb5-mips64 merge, but I've
finally repaired PSU of my NEC Express5800/230 R4400 PCI (NEC-JC94)
and committed fixes to make NetBSD/arc kernel work again on it.

---
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    2018, 2019, 2020 The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 9.0 (GENERIC) #44: Fri May 29 15:44:13 JST 2020
	tsutsui@mirage:/s/netbsd-9/src/sys/arch/arc/compile/GENERIC
NEC Express 5800/230 R4400 PCI
total memory = 256 MB
avail memory = 246 MB
timecounter: Timecounters tick every 10.000 msec
mainbus0 (root)
cpu0 at mainbus0: MIPS R4400 CPU (0x460) Rev. 6.0 with MIPS R4010 FPC Rev. 0.0
cpu0: 48 TLB entries, 16MB max page size
cpu0: 16KB/32B direct-mapped L1 instruction cache
cpu0: 16KB/32B direct-mapped write-back L1 data cache
cpu0: 1024KB/64B direct-mapped write-back L2 unified cache
jazzio0 at mainbus0
timer0 at jazzio0 addr 0xe00001a8
mcclock0 at jazzio0 addr 0xe0004000: mc146818 compatible time-of-day clock
lpt0 at jazzio0 addr 0xe0008000 intr 0
fdc0 at jazzio0 addr 0xe000c000 intr 1
fd0 at fdc0 drive 0: 1.44MB, 80 cyl, 2 head, 18 sec
AD1848 at jazzio0 addr 0xe0010000 intr 2 not configured
sn0 at jazzio0 addr 0xe0001000 intr 3: SONIC Ethernet
sn0: Ethernet address 00:00:4c:a1:30:48
osiop0 at jazzio0 addr 0xe0003000 intr 5: NCR53C710 rev 2, 50MHz, SCSI ID 7
scsibus0 at osiop0: 8 targets, 8 luns per target
osiop1 at jazzio0 addr 0xe0002000 intr 4: NCR53C710 rev 2, 50MHz, SCSI ID 7
scsibus1 at osiop1: 8 targets, 8 luns per target
pckbc0 at jazzio0 addr 0xe0005000 intr 6
pckbd0 at pckbc0 (kbd slot)
wskbd0 at pckbd0 (mux ignored): console keyboard
pms0 at pckbc0 (aux slot)
wsmouse0 at pms0 (mux ignored)
pms at jazzio0 addr 0xe0005000 intr 7 not configured
com0 at jazzio0 addr 0xe0006000 intr 8: ns16550a, working fifo
com0: txfifo disabled
com1 at jazzio0 addr 0xe0007000 intr 9: ns16550a, working fifo
com1: txfifo disabled
necpb0 at mainbus0
pci0 at necpb0 bus 0
pci0: i/o space, memory space enabled
pci_mem_find: 64-bit memory map which is inaccessible on a 32-bit platform
vendor 1033 product 0005 (miscellaneous bridge, revision 0x02) at pci0 dev 1 function 0 not configured
vendor 8086 product 0482 (miscellaneous prehistoric, revision 0x04) at pci0 dev 2 function 0 not configured
tga0 at pci0 dev 3 function 0: DC21030 step C, board type T8-02
tga0: 1024 x 768, 8bpp, Bt485 RAMDAC
tga0: interrupting at int D
wsdisplay0 at tga0 (kbdmux ignored): console (std, vt100 emulation), using wskbd0
timecounter: Timecounter "clockinterrupt" frequency 100 Hz quality 0
timecounter: Timecounter "mips3_cp0_counter" frequency 100000000 Hz quality 100
scsibus0: waiting 2 seconds for devices to settle...
scsibus1: waiting 2 seconds for devices to settle...
sd0 at scsibus0 target 0 lun 0: <MELCO, DSC-UE8.3G, 1.05> disk fixed
sd0: 8010 MB, 18988 cyl, 8 head, 108 sec, 512 bytes/sect x 16405632 sectors
sd0: sync (100.00ns offset 8), 8-bit (10.000MB/s) transfers
cd0 at scsibus0 target 4 lun 0: <YAMAHA, CRW8424S, 1.0f> cdrom removable
cd0: sync (100.00ns offset 8), 8-bit (10.000MB/s) transfers
boot device: sd0
root on sd0a dumps on sd0b
root file system type: ffs
kern.module.path=/stand/arc/9.0/modules

---

There were two problems:

- MIPS_CURLWP (t8) register reserved by NetBSD/mips kernel was not
  preserved on early ARC BIOS calls then stack pointer (and other
  structure data) were not initialized properly
   https://mail-index.netbsd.org/source-changes/2020/05/29/msg117858.html

- GENERIC (and RAMDISK) kernels became too large to be loaded by
  ARC BIOS functions (ARC BIOS uses around both 0x80100000 and
  0x807f0000 so we can only use ~6MB region to load kernel)
   https://mail-index.netbsd.org/source-changes/2020/05/29/msg117859.html
   https://mail-index.netbsd.org/source-changes/2020/05/29/msg117860.html

Note both problems don't affects GXemul PICA emulation because
it emulates ARC BIOS functions internally without real ROM binaries.

I'll sent a pullup request of these fixes so that NetBSD/arc 9.1
will work again.

Have fun,
---
Izumi Tsutsui