Newer HP machines (#Elitebook laptops, #Elitedesk desktops) seem to be woefully incompatible with #OpenBSD.
During boot, both the regular kernel and the ramdisk kernel hang at "entry point at 0x1001000". After tinkering for literal hours (BIOS options, different boot mediums, different versions, etc) I managed to get it working.
The problem is with the memory space. It can be fixed relatively simple with a custom kernel that uses a different address space. Here is the patch: https://marc.info/?l=openbsd-tech&m=161674750427354&w=2
Now running OpenBSD-current on an Elitebook with an eleventh gen Intel i5. The special keys (screen brightness, volume, etc) work out of the box 