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Which DECnet interfaces support remote, unattended, booting?

by bqt＠softjar.se

On 2013-05-17 17:43, Bob Armstrong wrote: Johnny Billquist wrote: Um, no. The "small program" is a program expected to be executed by the host. You missed my point - the issue was not "where does the small program execute from", it was "where is the code for the boot program stored (permanently) before it gets DMAed into the host". :-) Yes. My mistake. Johnny

12 years, 4 months

Which DECnet interfaces support remote, unattended, booting?

by bqt＠softjar.se

On 2013-05-17 17:40, Johnny Billquist wrote: On 2013-05-17 17:34, Bob Armstrong wrote: John Wilson wrote: They DMA a small program into memory Ah, I was wondering about that, because there aren't any separate boot ROMs on the DEUNA. I bet the "small program" is just part of the T11 code. Um, no. The "small program" is a program expected to be executed by the host. And on re-reading I see that I misunderstood the comment. Yes, the program to DMA into the host is located along with all the other code on the controller (a T11 for the DEUNA, and a 68K for the DELUA). Johnny

12 years, 4 months

Which DECnet interfaces support remote, unattended, booting?

by bob＠jfcl.com

Johnny Billquist wrote: Um, no. The "small program" is a program expected to be executed by the host. You missed my point - the issue was not "where does the small program execute from", it was "where is the code for the boot program stored (permanently) before it gets DMAed into the host". Bob

12 years, 4 months

Which DECnet interfaces support remote, unattended, booting?

by bob＠jfcl.com

Paul_Koning at Dell.com wrote: boot support doesn't make any sense in a software DDCMP implementation .... I was also wondering if, say, the DLV11 DDCMP driver in DECnet implemented booting. As you say, it's not as useful as an independent hardware boot in the controller, but it would work as long as enough of the OS is still alive to process DLV11 interrupts. You've got maybe a 50-50 chance, but even still - async DECnet was a low end solution so you expect low end results :-) The DDCMP driver wouldn't have to actually do the boot - there is a DECnet boot ROM for asynchronous interfaces already, and you could just assume that was already set up. All the DDCMP driver would have to do is start it. Bob

12 years, 4 months

Which DECnet interfaces support remote, unattended, booting?

by bqt＠softjar.se

On 2013-05-17 17:34, Bob Armstrong wrote: John Wilson wrote: this is a ridiculous security risk so that's why MOP had a magic number Yep, even the DMR has a boot "password", which is just an 8 bit value set by dip switches on the board, that has to match up with the MOP message. I don't remember how you set the password on the DEUNA/DELUA, it might be something you programmed, so by default it was a known value, but as soon as the system have started up, it can change it to something else, or even disable the trigger ability (maybe). They DMA a small program into memory Ah, I was wondering about that, because there aren't any separate boot ROMs on the DEUNA. I bet the "small program" is just part of the T11 code. Um, no. The "small program" is a program expected to be executed by the host. And I'm assuming that this scheme didn't work on any UNIBUS VAXes - only PDPs. Correct. :-) Johnny

12 years, 4 months

Which DECnet interfaces support remote, unattended, booting?

by Paul_Koning＠Dell.com

On May 17, 2013, at 11:34 AM, Bob Armstrong wrote: John Wilson wrote: this is a ridiculous security risk so that's why MOP had a magic number Yep, even the DMR has a boot "password", which is just an 8 bit value set by dip switches on the board, that has to match up with the MOP message. They DMA a small program into memory Ah, I was wondering about that, because there aren't any separate boot ROMs on the DEUNA. I bet the "small program" is just part of the T11 code. And I'm assuming that this scheme didn't work on any UNIBUS VAXes - only PDPs. That sounds right. The network interface needs a way to tell the machine to restart. On a VAX, the Unibus doesn't do that. In theory you could have a console front end processor that implements MOP Boot message handling and does the restart if it sees one. (The same would be true on PDP-10 or -20 machines that have a front end processor.) In practice, I don't remember that such a thing was ever done. paul

12 years, 4 months

Which DECnet interfaces support remote, unattended, booting?

by bob＠jfcl.com

John Wilson wrote: this is a ridiculous security risk so that's why MOP had a magic number Yep, even the DMR has a boot "password", which is just an 8 bit value set by dip switches on the board, that has to match up with the MOP message. They DMA a small program into memory Ah, I was wondering about that, because there aren't any separate boot ROMs on the DEUNA. I bet the "small program" is just part of the T11 code. And I'm assuming that this scheme didn't work on any UNIBUS VAXes - only PDPs. Bob

12 years, 4 months

Which DECnet interfaces support remote, unattended, booting?

by bqt＠softjar.se

On 2013-05-17 17:18, John Wilson wrote: From: "Bob Armstrong" <bob at jfcl.com> I thought I remembered that the Ethernet interfaces could do it, but how does that work? Sneakily. It's in the DEUNA/DELUA manuals. They DMA a small program into memory, including the power fail vector (24/26 I think?) which points at it, and then fake a power failure while blocking INIT L to themselves. Obviously this is a ridiculous security risk (I guess they assumed the ethernet coax was physically secure) so that's why MOP had a magic number (which could be 0 in earlier versions but not in later revs). Your memory is way better than mine. :-) Thanks. That summary made me recall details. The DEQNA/DELQA were kludgier and I'm drawing a blank on whether they even support network-triggered booting. I think I remember seeing the DELQA being able to. The DEUNA/DELUA/DEQNA/DELQA has no reason to implement DDCMP, although it certainly had enough local CPU power to do so. Did it still scan for MOP trigger messages anyway? DEUNA/DELUA support MOP dump/load/sysID (as well as ECT echo) in firmware, I'm blanking on which parts of MOP the DELQA knows innately (I think at least enough to send system IDs), and the DEQNA is too mindless to do anything w/o driver help. :-) Johnny

12 years, 4 months

Which DECnet interfaces support remote, unattended, booting?

by wilson＠dbit.com

From: "Bob Armstrong" <bob at jfcl.com> I thought I remembered that the Ethernet interfaces could do it, but how does that work? Sneakily. It's in the DEUNA/DELUA manuals. They DMA a small program into memory, including the power fail vector (24/26 I think?) which points at it, and then fake a power failure while blocking INIT L to themselves. Obviously this is a ridiculous security risk (I guess they assumed the ethernet coax was physically secure) so that's why MOP had a magic number (which could be 0 in earlier versions but not in later revs). The DEQNA/DELQA were kludgier and I'm drawing a blank on whether they even support network-triggered booting. The DEUNA/DELUA/DEQNA/DELQA has no reason to implement DDCMP, although it certainly had enough local CPU power to do so. Did it still scan for MOP trigger messages anyway? DEUNA/DELUA support MOP dump/load/sysID (as well as ECT echo) in firmware, I'm blanking on which parts of MOP the DELQA knows innately (I think at least enough to send system IDs), and the DEQNA is too mindless to do anything w/o driver help. John Wilson D Bit

12 years, 4 months

Which DECnet interfaces support remote, unattended, booting?

by Paul_Koning＠Dell.com

On May 17, 2013, at 10:32 AM, Bob Armstrong wrote: I thought the DELQA did? I don't think the DEQNA did, however. Also, the DEUNA and DELUA handles it, as far as I know. I thought I remembered that the Ethernet interfaces could do it, but how does that work? The DMR required that you have a M9312 with the appropriate boot ROMs - were there NI boot ROMS for the M9312 too? How did the DELQA do it (i.e. which QBUS PDP-11 CPU had an NI boot ROM)? Also, the DMR was smart enough to implement DDCMP in "hardware" and so it understood MOP at least well enough to detect the TRIGGER message. The DEUNA/DELUA/DEQNA/DELQA has no reason to implement DDCMP, although it certainly had enough local CPU power to do so. Did it still scan for MOP trigger messages anyway? Or was the Ethernet trigger implemented differently? MOP is a protocol that's defined both for point to point links (DDCMP) and Ethernet, though some bits (like Sysid) apply only to one of those. But the Boot message (NCP TRIGGER) is common to both. The implementation of the boot message depends on machinery outside the CPU that can recognize and validate the boot message, and make the CPU reboot. So it's not very common -- boot support doesn't make any sense in a software DDCMP implementation, or a software MOP on Ethernet implementation. The reason is that it would only work if the software on the CPU is sane, which is precisely when you do not need to force a boot. So you only see it on controllers that have their own microprocessor to implement that part of MOP, and they need the ability to force a CPU restart from where they sit on the I/O bus. Unibus does that; I forgot if Qbus does. DMC and DMC have the necessary microprocessor, as do UNA and LUA. QNA does not. LQA has a microprocessor and could do this in principle, but I'm not sure if it actually does. KMC could, if it wanted to, but here too I don't know if anyone has done it. Note that downloading a system is separate from boot/trigger. Download requires a boot rom that talks to the network device to speak the MOP Load protocol. You can do that whenever the system restarts; it might be because of a power fail or crash. Conversely, it's possible for a MOP Boot (trigger) to reset the CPU and have that result in a boot from local storage, such as disk or tape. That's probably not common but the two operations are separate and it's certainly valid for that to be the result. paul

12 years, 4 months

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