Hi
On Tue, Oct 08, 2019 at 06:47:07AM -0700, Van De Ven, Arjan wrote:
We very strongly suggest that you idle the sibbling, and depending on your cpu model, you might need some other tweaks. It's best in general for the system to be as quiet as possible.
Since you say this is coreboot i'm assuming this is preboot before you bring up the OS.
If the sequence of bringup is that you bringup each logical cpu one at a time much like how Linux early boot is, then you don't have to worry. Since you would expect teh CPU is just waiting to boot in Wais-for-SIPI state.
You can see linux earlyboot simply checks if the version on the cpu is older than the one packaged in initrd, then we would apply the newer microcode.
Once the first thread in the core loads the microcode the thread-sibling would automatically
Boris provided excellant references to the Linux code for late-loading where the cpus are already doing work in the OS like scheduling, handling interrupts etc. Then those rules apply.
Cheers, Ashok