On Wed, May 29, 2024 at 09:49:48AM +0000, Christophe Leroy wrote: > Doesn't really matter if it's PUD or PMD at this point. On a 32 bits > kernel it will be all PMD while on a 64 bits kernel it is both PMD and PUD. > > At the time being (as implemented with hugepd), Linux support 4M, 16M, > 64M, 256M and 1G (Shifts 22, 24, 26, 28, 30) > > The hardware supports the following page sizes, and encodes them on 4 > bits allthough it is not directly a shift. Maybe it would be better to > use that encoding after all: I think so. > > 0001 4 Kbytes (Shift 12) > 0010 16 Kbytes (Shift 14) > 0011 64 Kbytes (Shift 16) > 0100 256 Kbytes (Shift 18) > 0101 1 Mbyte (Shift 20) > 0110 4 Mbytes (Shift 22) > 0111 16 Mbytes (Shift 24) > 1000 64 Mbytes (Shift 26) > 1001 256 Mbytes (Shift 28) > 1010 1 Gbyte (e500v2 only) (Shift 30) > 1011 4 Gbytes (e500v2 only) (Shift 32) You say hugehages start at 2MB (shift 21), but you say that the smallest hugepage Linux support is 4MB (shift 22).? -- Oscar Salvador SUSE Labs
