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> it allows to craft your own persistent microcode patch without external debugger. These are persistent? Meaning they survive reboots? Is it stored in flash m
by dataflow 5y ago
> it allows to craft your own persistent microcode patch without external debugger.
These are persistent? Meaning they survive reboots? Is it stored in flash memory on the CPU or something? I thought all microcode updates are re-applied on each boot.
- sabas123 5y agoIf you would override the default microcode update, which should be doable if you have that level of access, you could call it persistent no?
- dataflow 5y agoNot really honestly. I mean, I thought the microcode update is done by the firmware and/or the OS on boot. Assuming that's correct, whether it's performed or not is entirely dictated by those entities... not by anything related to the CPU. It's like saying "I'm moving to New York" just because there's a car that drives you there from New Jersey every day. And if you really want to call that 'persistent', I'm not sure how one might have a non-persistent update in that case?
- tamrix 5y agoMicrocode updates have to be reapplied each time you restart your system.
- marcan_42 5y agoThey mean you could put code into your UEFI to apply the patch using these instructions on every boot, as opposed to the state of affairs until now, when you needed an external debugger connected via DCI to do the same thing. The CPU still needs to be in the Red state, which means you need to control ME. This applies to both cases.
- dataflow 5y agoOh I see! Thanks!