Thoughts on software-defined silicon [LWN.net]

Thoughts on software-defined silicon

Posted Feb 18, 2022 18:46 UTC (Fri) by tshow (subscriber, #6411)
Parent article: Thoughts on software-defined silicon

According to my father, the IBM mainframe upgrade (at least on the mainframe his company had) involved a physical (door lock style) key that operated a rotary switch. Apparently there was a lot of Blues Brothers style pomp & circumstance (briefcase handcuffed to one of the IBM techs, many IBM people in the upgrade party and so forth) involved in the upgrade. His understanding was that they made a big deal of it for legal reasons. Between it requiring a key and all the ceremony, there was no way a customer could claim they didn't realize they couldn't just close a jumper for free.

I could kind of see the justification for this if it was running the hardware harder and making it more likely to fail within the warranty period, if (for example) they charged to let you dangerously overclock but would still honor the warranty. But this does look like another "The money people are asking where else can we extract rent?" situation.

Now, if you could pay them to get root access to the IME so you could properly secure the machine, that would be another thing entirely.

Thoughts on software-defined silicon

Posted Feb 19, 2022 12:48 UTC (Sat) by hazeii (guest, #82286) [Link]

On mainframes they were often call 'slugs', in that they essentially slowed the machine down - thus there were extra payments to deslug the machines (even on a short-term basis).

Thoughts on software-defined silicon

Posted Feb 22, 2022 1:28 UTC (Tue) by klossner (subscriber, #30046) [Link] (4 responses)

Many decades ago, my employer leased IBM 370/148 serial number 1. It was a lease not a purchase so we paid a monthly fee for the computing resource, and the fact that increasing RAM could be done by paying more each month to have a jumper moved was not philosophically troubling. It was analogous to renting a cloud server today.

Thoughts on software-defined silicon

Posted Feb 22, 2022 9:46 UTC (Tue) by geert (subscriber, #98403) [Link] (3 responses)

Except that the unused cloud server capacity would be rented to someone else.

Software-defined silicon is like renting the first two floors in a 10-story office building which is otherwise vacant: if you pay more, you get access to more floors; if you don't, the other floors stay unused. But the other floors have been constructed anyway, and thus have already consumed (scarce) resources.

Thoughts on software-defined silicon

Posted Feb 25, 2022 17:02 UTC (Fri) by giraffedata (guest, #1954) [Link] (2 responses)

If this building is analogous to a processor, how has constructing the other 8 floors consumed scarce resources? It costs about the same to build a 10 story building as a a 2 story one if they're like processors.

And that's why the the owner doesn't make you pay for all 10 stories if you don't need them.

And the only reason he doesn't go ahead and let you use the other 8 anyway is that locking you out of them is the only way he can know you're telling the truth when you say you're willing to pay for only 2 stories. Charging people for all the stories they're willing to pay for minimizes the price per story for everyone.

Thoughts on software-defined silicon

Posted Feb 25, 2022 18:58 UTC (Fri) by geert (subscriber, #98403) [Link]

> If this building is analogous to a processor, how has constructing the other 8 floors consumed scarce resources? It costs about the same to build a 10 story building as a a 2 > story one if they're like processors.

The "10-story" processor still requires more raw material (silicon + whatever else for doping, etching, interconnects, ...). Plus, you can fit more "2 story" processors on the same wafer, so there's a processing cost, too.

Thoughts on software-defined silicon

Posted Feb 25, 2022 19:06 UTC (Fri) by nybble41 (subscriber, #55106) [Link]

As long as we're speaking in analogies, it's more like *buying* (not renting) the building but the seller only gives you the key to the first two stories. You are, after all, *buying* the entire CPU, even if parts of it are disabled by software keys.

The difference being that it's not a crime to pick or drill out some locks in your own building to access the upper floors. If you were actually renting the building (CPU) that would be a different matter. (And, of course, that the software locks in question are considerably more difficult to either pick or disable than, say, the lock on your average bank vault, much less a normal high-rise.)

Thoughts on software-defined silicon

Posted Feb 27, 2022 3:07 UTC (Sun) by eean (subscriber, #50420) [Link]

> I could kind of see the justification for this if it was running the hardware harder and making it more likely to fail within the warranty period

yeah the Tesla battery thing actually might make sense since not fully charging the battery is better for its longevity and one presumes/hopes that as the battery ages unused cells can be cycled in as others wear out. so you're basically paying extra to optimize for range instead of longevity.

Hard to imagine Intel having something analogous to this though.