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Comment by miczyg | Hacker News Reader

It is not so easy on servers. The AMD servers platforms perform RAM training on each boot, even before the CPU starts execution the firmware. So no matter of your BIOS/coreboot performance, you have a guaranteed 2min++ boot time (depending on amount of RAM and CPU sockets), because of memory training... There is no concept of fastboot from the cold boot like on Intel silicon.

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Memory training or memory testing leading to the minutes long time spent in firmware?

I haven't used the most recent AMD server platforms, but on earlier Epyc generations the memory training and PCIe link training were noticed durations but measured in seconds, not minutes. Turning on debug for the PSP could turn this into minutes but would also show all the results of the memory training sequences. The memory testing would take minutes but was easily disabled to reduce the boot time. Has this changed in the newer Epyc generations?

Memory training taking minutes on AMD systems isn't unusual. On my desktop with a 7800X3D and 64 GB of RAM, I get scared whenever the system needs to do the training again. Because it just sits there at a black screen for a couple minutes while it does the training. I have to just wait and hope that it's doing something and not that my system is dead.

My big AMD server with 2TB RAM and a couple of H100's needs about 15m to boot. Servers are different kinds of machines.

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