Intel's "redundant prefix issue"

Posted Nov 16, 2023 6:24 UTC (Thu) by donald.buczek (subscriber, #112892)
In reply to: Intel's "redundant prefix issue" by pizza
Parent article: Intel's "redundant prefix issue"

> If microcode updates can patch/work around vulnerabilities, they can also _add_ them.

So what? I'm free to add bad kernel code, bad userspace code, enter `rm -rf /` or us a hammer on my cpu.

Agreed, people could be tricked to install bad microcode, e.g. by a false promise of performance gain, and brick their systems. But that only justifies a warning, not preventing people from installing whatever microcode they want.

Intel's "redundant prefix issue"

Posted Nov 16, 2023 19:34 UTC (Thu) by Cyberax (✭ supporter ✭, #52523) [Link] (9 responses)

Bad microcode can cause physical damage from overheating. And then you sell your subtly broken CPU on eBay.

Intel's "redundant prefix issue"

Posted Nov 17, 2023 9:17 UTC (Fri) by james (subscriber, #1325) [Link] (3 responses)

How is this different from overclocking?

Intel's "redundant prefix issue"

Posted Nov 17, 2023 16:55 UTC (Fri) by Cyberax (✭ supporter ✭, #52523) [Link] (2 responses)

Modern CPUs have active power management, so they likely won't be damaged by overclocking.

Intel's "redundant prefix issue"

Posted Nov 20, 2023 7:34 UTC (Mon) by eduperez (guest, #11232) [Link] (1 responses)

Is the power management part of the microcode, or can it be affected by a buggy or malignant microcode?

Intel's "redundant prefix issue"

Posted Nov 20, 2023 19:11 UTC (Mon) by Cyberax (✭ supporter ✭, #52523) [Link]

It most definitely is a part of the microcode. A part of it works in runtime via SMM: https://en.wikipedia.org/wiki/System_Management_Mode

Intel's "redundant prefix issue"

Posted Nov 17, 2023 12:05 UTC (Fri) by paulj (subscriber, #341) [Link] (4 responses)

Bad graphics drivers can burn out your monitor - they certainly could back with CRTs in the 90s; I bet they can still damage graphics cards today.

Ergo, graphics drivers must be kept closed.

Intel's "redundant prefix issue"

Posted Nov 17, 2023 16:56 UTC (Fri) by Cyberax (✭ supporter ✭, #52523) [Link] (3 responses)

> I bet they can still damage graphics cards today.

I don't think so? All the modern display protocols (HDMI, DisplayPort) are digital.

Intel's "redundant prefix issue"

Posted Nov 17, 2023 17:26 UTC (Fri) by paulj (subscriber, #341) [Link] (2 responses)

I was referring to heat wrt modern cards. Thermal power management on some cards can be disabled.

Regardless, the point is this argument "But the software could damage the hardware!" argument is not new. It was also valid in the 90s to 00s for graphics hardware. Had this argument been held as valid then, we couldn't have had open graphics drivers then.

It's just not a good argument.

Intel's "redundant prefix issue"

Posted Nov 18, 2023 2:07 UTC (Sat) by Cyberax (✭ supporter ✭, #52523) [Link] (1 responses)

> I was referring to heat wrt modern cards. Thermal power management on some cards can be disabled.
> Had this argument been held as valid then, we couldn't have had open graphics drivers then.

I hate to break this to you, but modern graphics cards _also_ rely on signed firmware. That's why NVidia cards had been so useless with open drivers until recently, the only allowed firmware was locked to the lowest power management setting.

Intel's "redundant prefix issue"

Posted Nov 20, 2023 10:19 UTC (Mon) by paulj (subscriber, #341) [Link]

I'm well aware. Just saying these are not good arguments as to why firmware must be closed.