alt Hacker NewsYeah, it's the firmware. It's an AM4 board, and the BIOS only gives PCI devices the space from the top of RAM up to 512 GB. Each 32 GB BAR has to start on a 32 GB boundary, and its small doorbell BAR spills into the next slot, so each card needs 64 GB. Six won't fit. So I turn Resizable BAR off in the BIOS and resize the four R9700s from Linux, where I hit the kernel bug.
Replies
InsidiousWombat • today at 5:25 PM
"640kB ought to be enough for everyone" moment.
I wonder if AI could RE the BIOS enough to fix that limit
The problem is that with P2P every card will map every other card into its address space. So you're not mapping 128G but likely 512! It depends a bit on what software you use, some software is smart about this and uses a smaller sliding window if it can't use all of it at once and some software is really rigid.