[Info-vax] axpbox crashed when logged out.

[Remy]

Op woensdag 18 november 2020 om 16:05:56 UTC+1 schreef Stephen Hoffman:
> On 2020-11-18 03:34:02 +0000, Timothy Stark said: 
> 
> > I discovered a bug in axpbox when I attempted to log out. Axpbox 
> > crashed with messages: 
> > 
> > 
> > Exception in SYM thread: Not implemented: pci0.1(sym53c810).disk0.4(file): 
> > Unknown SCSI command 0x1b. 
> > 
> > : /home/sword7/axpbox/src/src/Disk.cpp, line 1495. 
> > 
> > Emulator Failure: Threading error: SYM thread has died: 
> > /home/sword7/axpbox/src/src/Sym53C810.cpp, line 1501 
> > 
> > Stop threads: cpu0 srl0 sym ali kbd 
> > 
> > Freeing memory in use by system... 
> > 
> > pci0.1(sym53c810).disk0.0(file): Closing file. 
> > 
> > 
> > 
> > I checked SCSI reference for command 0x1B and it performs 
> > loading/unloading or starting/stopping unit. I believe that logout 
> > routines attempted to unload CD om DKA400 (53C810). 
> > 
> > I was able reproduce errors at some chance when I attempted to log off. 
> > 
> > 
> > Does anyone have any experience with that?
> Any experience with emulated hardware issues, and with actual hardware 
> having issues? Sure. This case is basically buggy hardware. 
> 
> Experience with SCSI issues? Absolutely. Lots. 
> 
> With this particular emulator and this issue? No. 
> 
> Check with the emulator maintainer. axpbox hasn't been getting all 
> that much traffic around here as yet, and I don't know that the 
> maintainer follows this usenet newsgroup or receives feedback from 
> postings here. 
> 
> Or have a look at the emulator itself. At the emulator source code. 
> Solely from what you've posted and not having reviewed the source code, 
> this looks like a fairly reasonable setup within the emulator code. 
> 
> SCSI 0x1b is start-stop and load-unload. Prolly a stop request, here. 
> An unload is possible and certainly easy to test, but OpenVMS doesn't 
> unload devices at shutdown, nor at logout. Start-stop and load-unload 
> are not really particularly relevant commands for an emulator, so it 
> can likely be ignored save for updating some internal device state 
> settings within the emulator. Pull down the emulator source code and 
> have a look at the Disk.cpp and Sym53C810.cpp source code, and at 
> whatever code parses the SCSI command packets and generates the SCSI 
> command responses. 
> 
> Based on what the OpenVMS shutdown does and on what logout does and 
> what the emulator is reporting, I'd suspect this is a disk spindown 
> request. 
> 
> SCSI is a command-response protocol, so OpenVMS drivers and some 
> user-written apps send SCSI commands at the SCSI controller or the SCSI 
> device, and the device then parses and processes the command request 
> and generates what the device considers an appropriate response. Part 
> of the "fun" of SCSI is the flexibility and variability of the 
> possible responses and of the timing of same. SCSI's gotten easier to 
> deal with in the last decade or two, but it's still possible to bump 
> into incompatibilities and unimplemented commands and unexpected 
> responses. SCSI weirdness was far more common in past years, and 
> OpenVMS SCSI processing itself has gotten better. V6.2 and V7.1 saw 
> substantial improvements, there. 
> 
> In this case, the emulator doesn't recognize the SCSI command, and 
> crashes. SCSI hardware and particularly SCSI firmware does that 
> sometimes, too—crashes, lock-ups, hangs. 
> 
> FWIW, USB is basically SCSI with random bus disconnects, and ATAPI is 
> basically SCSI operating atop IDE. 
> 
> I'd probably add command packet dump to that crash code; a way to dump 
> the full SCSI command packet to the user. Longer-term, I'd usually just 
> write the above crash info and the command buffer to a logfile 
> somewhere or to a crash report that can be available to the maintainer, 
> and generate some benign description to the user; an I/O feature not 
> implemented by this version of the emulator, in this case. With where 
> to look for more data and/or how to report this error and/or seeking 
> permission to upload the related telemetry. 
> 
> -- 
> Pure Personal Opinion | HoffmanLabs LLC

Thank you Stephen for your information. I've added it to the github issue Tim created: https://github.com/lenticularis39/axpbox/issues/36, should help in resolving it.

I think Tomáš is aware of this google group / mailing list but I'm not sure he follows it via email (just the website).