(sorry, I had to trim https from the front of the URLs because I have just created this account to post the bug and am not allowed to post URLs for 24 hrs) In this section: wiki.gentoo.org/wiki/Handbook:AMD64/Installation/Kernel#Alternative:_Using_genkernel it says: "If the partitioning example from the handbook is followed, then this device is most likely /dev/sda1 with the ext4 file system." However the referenced section wiki.gentoo.org/wiki/Handbook:AMD64/Installation/Disks#Default_partitioning_scheme of the handbook now actually says: "/dev/sda1 fat32 (UEFI) or ext4 (BIOS)" and nowadays I imagine most new installs are on UEFI not BIOS, either way just ext4 is definitellz misleading should be at least: "If the partitioning example from the handbook is followed, then this device is most likely /dev/sda1 with the fat32 (for UEFI installations) or ext4 (for BIOS installation) file system."
Let me know if I can actually help to fix the documentation instead of just submitting bugs!
*** Bug 854270 has been marked as a duplicate of this bug. ***
I think Maffblaster handled this in https://wiki.gentoo.org/index.php?title=Handbook:Parts/Installation/Kernel&diff=1185390&oldid=1185310. Thanks!