New pmap module for m68k

[Jason Thorpe <thorpej%me.com@localhost>]

Hey folks,

In the evenings over the last couple of weeks I’ve been working on a new pmap module for the m68k ports.  The intention is to address the fundamental limitations of the classical Hibler pmap (pmap_motorola.c) with regard to the 68040.  The new module has a completely different page table management strategy and natively works with the 3-level table configuration of the 68040 while also natively working with he mandatory 2-level configuration imposed by the HP MMU found in the HP 9000/320 and 9000/350.

One of the reasons I wanted to do this is so that larger memory configs can be supported on 68040.  Currently, 68040 systems suffer from address space exhaustion because of the way the 3-level MMU tables were shoehorned into the Hibler pmap.  This morning, I successfully booted NetBSD/virt68k multi-user with a 2G RAM configuration using the new pmap.  With luck, this will make pkgsrc building for m68k a lot easier!

Some work will be required to integrate this with other m68k ports, pmap_bootstrap1() specifically needs to gain some additional capabilities to make it per-platform adaptable (I do *not* want to end up with a separate copy per port).  The Amiga and Atari ports are going to be a heavier lift because they’re odd-ball in their early bootstrap compared to the others.  Definitely looking for help in this aspect, so drop me an email if you’re interested in helping with the effort and have hardware (or a decently functioning emulator) that can be used for testing.



WARNING: Image format was not specified for 'disk1.raw' and probing guessed raw.
         Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
         Specify the 'raw' format explicitly to remove the restrictions.
WARNING: Image format was not specified for 'disk0.raw' and probing guessed raw.
         Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
         Specify the 'raw' format explicitly to remove the restrictions.
[   1.0000000] Initialized Goldfish TTY console @ 0xff008000
[   1.0000000] Memory segment 0: addr=0x00633000 size=0x7f9cd000
[   1.0000000] entropy: ready
[   1.0000000] pmap_growkernel: initial_kernel_ptpages=515, initial_kernel_stpages=9
[   1.0000000] pmap_growkernel: requested maxkvaddr=0x02796000
[   1.0000000] pmap_growkernel: returning=0x80c00000
[   1.0000000] Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
[   1.0000000]     2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013,
[   1.0000000]     2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023,
[   1.0000000]     2024, 2025
[   1.0000000]     The NetBSD Foundation, Inc.  All rights reserved.
[   1.0000000] Copyright (c) 1982, 1986, 1989, 1991, 1993
[   1.0000000]     The Regents of the University of California.  All rights reserved.

[   1.0000000] NetBSD 11.99.3 (GENERIC) #109: Sun Nov  9 09:28:16 PST 2025
[   1.0000000] thorpej@dhcp-171.ktnet:/Users/thorpej/NetBSD/current/m68k/src/sys/arch/virt68k/compile/GENERIC
[   1.0000000] Qemu 9.1.0: MC68040+MMU+FPU, 4k+4k on-chip physical I/D caches
[   1.0000000] total memory = 2048 MB
[   1.0000000] avail memory = 2010 MB
[   1.0000000] mainbus0 (root)
[   1.0000000] gfpic0 at mainbus0 addr 0xff000000: Google Goldfish PIC
[   1.0000000] gfpic0: interrupting at IPL 1
[   1.0000000] gfpic1 at mainbus0 addr 0xff001000: Google Goldfish PIC
[   1.0000000] gfpic1: interrupting at IPL 2
[   1.0000000] gfpic2 at mainbus0 addr 0xff002000: Google Goldfish PIC
[   1.0000000] gfpic2: interrupting at IPL 3
[   1.0000000] gfpic3 at mainbus0 addr 0xff003000: Google Goldfish PIC
[   1.0000000] gfpic3: interrupting at IPL 4
[   1.0000000] gfpic4 at mainbus0 addr 0xff004000: Google Goldfish PIC
[   1.0000000] gfpic4: interrupting at IPL 5
[   1.0000000] gfpic5 at mainbus0 addr 0xff005000: Google Goldfish PIC
[   1.0000000] gfpic5: interrupting at IPL 6
[   1.0000000] gfrtc0 at mainbus0 addr 0xff006000: Google Goldfish RTC + timer
[   1.0000000] gfrtc0: hardclock interrupting at gfpic5 irq 1 (IPL 6)
[   1.0000000] gfrtc0: Using as delay() timer.
[   1.0000000] gfrtc1 at mainbus0 addr 0xff007000: Google Goldfish RTC + timer
[   1.0000000] gfrtc1: using as Time of Day Register.
[   1.0000000] gftty0 at mainbus0 addr 0xff008000: Google Goldfish TTY
[   1.0000000] gftty0: console
[   1.0000000] gftty0: interrupting at gfpic0 irq 32 (IPL 1)
[   1.0000000] virtctrl0 at mainbus0 addr 0xff009000: Qemu Virtual System Controller
[   1.0000000] virtctrl0: features=0x00000001
[   1.0000000] virtio0 at mainbus0 addr 0xff01f600
[   1.0000000] virtio0: VirtIO-MMIO-v2
[   1.0000000] virtio0: network device (id 1, rev. 0x01)
[   1.0000000] vioif0 at virtio0: features: 0x130870020<V1,EVENT_IDX,INDIRECT_DESC,CTRL_MAC,CTRL_RX,CTRL_VQ,STATUS,MAC>
[   1.0000000] vioif0: Ethernet address 52:54:00:12:34:56
[   1.0000000] virtio0: interrupting at gfpic4 irq 28 (IPL 5)
[   1.0000000] virtio1 at mainbus0 addr 0xff01f800
[   1.0000000] virtio1: VirtIO-MMIO-v2
[   1.0000000] virtio1: SCSI device (id 8, rev. 0x01)
[   1.0000000] vioscsi0 at virtio1: features: 0x110000000<V1,INDIRECT_DESC>
[   1.0000000] vioscsi0: cmd_per_lun 128 qsize 1024 seg_max 254 max_target 255 max_lun 16383
[   1.0000000] virtio1: interrupting at gfpic4 irq 29 (IPL 5)
[   1.0000000] scsibus0 at vioscsi0: 256 targets, 16384 luns per target
[   1.0000000] virtio2 at mainbus0 addr 0xff01fa00
[   1.0000000] virtio2: VirtIO-MMIO-v2
[   1.0000000] virtio2: entropy device (id 4, rev. 0x01)
[   1.0000000] viornd0 at virtio2: features: 0x110000000<V1,INDIRECT_DESC>
[   1.0000000] virtio2: interrupting at gfpic4 irq 30 (IPL 5)
[   1.0000000] virtio3 at mainbus0 addr 0xff01fc00
[   1.0000000] virtio3: VirtIO-MMIO-v2
[   1.0000000] virtio3: block device (id 2, rev. 0x01)
[   1.0000000] ld0 at virtio3: features: 0x110002e54<V1,INDIRECT_DESC,DISCARD,CONFIG_WCE,TOPOLOGY,FLUSH,BLK_SIZE,GEOMETRY,SEG_MAX>
[   1.0000000] ld0: max 254 segs of max 65536 bytes
[   1.0000000] virtio3: interrupting at gfpic4 irq 31 (IPL 5)
[   1.0000000] ld0: 8193 MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 16779264 sectors
[   1.0000000] virtio4 at mainbus0 addr 0xff01fe00
[   1.0000000] virtio4: VirtIO-MMIO-v2
[   1.0000000] virtio4: block device (id 2, rev. 0x01)
[   1.0000000] ld1 at virtio4: features: 0x110002e54<V1,INDIRECT_DESC,DISCARD,CONFIG_WCE,TOPOLOGY,FLUSH,BLK_SIZE,GEOMETRY,SEG_MAX>
[   1.0000000] ld1: max 254 segs of max 65536 bytes
[   1.0000000] virtio4: interrupting at gfpic4 irq 32 (IPL 5)
[   1.0000000] ld1: 16384 MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 33554432 sectors
[   1.0000000] No statclock; using hardclock.
[   1.0000000] Initialzing hardclock: freq=100 Hz, interval=10000 usec
[   1.1300030] cd0 at scsibus0 target 6 lun 0: <QEMU, QEMU CD-ROM, 2.5+> cdrom removable
[   1.1300030] cd0: async, 8-bit transfers, tagged queueing
[   4.9200030] swwdog0: software watchdog initialized
[   4.9400030] root on ld0a dumps on ld0b
[   4.9600030] root file system type: ffs
[   4.9600030] kern.module.path=/stand/virt68k/11.99.3/modules
Sun Nov  9 09:33:21 PST 2025
Starting root file system check:
/dev/rld0a: file system is clean; not checking
Setting sysctl variables:
ddb.onpanic: 1 -> 0
swapctl: setting dump device to /dev/ld0b
swapctl: adding /dev/ld0b as swap device at priority 0
Starting file system checks:
/dev/rld1a: file system is clean; not checking
Loaded entropy from /var/db/entropy-file.
Waiting for entropy...done
Setting tty flags.
Starting network.
Hostname: virt68k
IPv6 mode: host
Configuring network interfaces: vioif0.
Adding interface aliases:.
Waiting for duplicate address detection to finish...
Starting dhcpcd.
Starting mdnsd.
Building databases: dev, utmp, utmpx.
Starting syslogd.
Nov  9 09:33:35 virt68k syslogd[427]: /var/log/messages: No such file or directory
Nov  9 09:33:35 virt68k syslogd[427]: /var/log/messages: No such file or directory
Mounting all file systems...
Clearing temporary files.
Creating a.out runtime link editor directory cache.
Checking quotas: done.
Setting securelevel: kern.securelevel: 0 -> 1
swapctl: setting dump device to /dev/ld0b
Starting virecover.
Checking for core dump...
savecore: no core dump
Starting local daemons:.
Updating motd.
Starting ntpd.
Starting sshd.
Starting inetd.
Starting cron.
Sun Nov  9 09:33:40 PST 2025

NetBSD/virt68k (virt68k) (constty)

login: 

-- thorpej