Re: NetBSD on SIMH, but not microvax3900

On Thu, 2024-03-07 13:56:02 -0500, Mouse <[email protected]> wrote:
> [simh-780 boot fail]
> > set cpu 128M
> 
> > Suggestions for debugging it?
> 
> Is 128 megs a possible memory config for a 780?  (That's a real
> question; I don't know the 780 enough to answer it myself.)

I don't have/know the hardware, so I don't know. Just gave it a try
with 8 MB and 16 MB, both failed the same way.

  However, I made a new observation: I accidentally hit the SPACE key
while waiting for "Press any key to abort autoboot 5", then gave it a
"boot netbsd" and expected it to restart. However, this time, it's
hanging instead of looping:

============================= 8< ------------------------------------
root@lili:/var/cache/laminar-vm/vax780# ./BIN/vax780 *cnf

VAX 11/780 simulator V4.0-0 Current        git commit id: 9a73eb9d
/var/cache/laminar-vm/vax780/rpi_vax780.cnf-36> at xu tap:trap_17
Command not allowed
/var/cache/laminar-vm/vax780/rpi_vax780.cnf-42> boot rq3
Loading boot code from internal vmb.exe

>> NetBSD/vax boot [1.12 ()] <<
>> Press any key to abort autoboot 4
getdisklabel: no disk label
nfs_open: must mount first.
open netbsd.vax: No such file or directory
> boot netbsd
getdisklabel: no disk label
nfs_open: must mount first.
4405588+185132 [255216+240258]=0x4da004
Loading boot code from internal vmb.exe
Rebooting...

>> NetBSD/vax boot [1.12 ()] <<
>> Press any key to abort autoboot 5
Press '?' for help
> ?
Commands:
?       Show this help menu
help    Same as '?'
boot    Load and execute file
halt    Halts the system
> boot netbsd
getdisklabel: no disk label
nfs_open: must mount first.
4405588+185132 [255216+240258]=0x4da004
----------------------------- >8 ====================================

> I'm wondering if there might be 780-specific code that assumes things
> like the maximum physical memory a 780 can actually have.  Something
> like, maybe, the memory sizing code assuming arithmetic won't overflow
> because the memory size can't be greater than whatever....

8 to 16 MB sounds at least reasonable. Maybe it could hold 128 MB,
but let's not stretch it too far.

> I also notice a "Command not allowed" during startup.  I don't know
> enough to know, but that strikes me as at least potentially relevant.

SIMH noticed it couldn't attach to the TAP device "trap_17", which I
missed to create and add to the bridge. If it had booted, it would
have had no working network...

MfG, JBG

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