CVSROOT: /cvs
Module name: src
Changes by: [email protected] 2013/11/24 15:08:25
Modified files:
sys/arch/vax/include: pcb.h pmap.h pte.h
sys/arch/vax/vax: genassym.cf locore.S machdep.c pmap.c trap.c
vm_machdep.c
Log message:
Rework pmap to use dynamic P0 and P1 region allocation, instead of allocating
the largest possible page table for every pmap; from NetBSD. This allows the
kernel to use much less memory for page tables.
Significant differences against the NetBSD code are:
- allocation of page table pages is done with a pool instead of allocating
whole logical pages from uvm and managing the freelist within pmap, never
releasing allocated pages.
- try to use pt_entry_t * rather than int * whenever possible.
- growth of P0 and P1 regions is allowed to fail, if invoked from
pmap_enter with the PMAP_CANFAIL flag. This will stall processes until
memory for the page tables can be obtained, rather than panicing, in
most cases.
- keep management of mappings for managed pages using pv lists tied to the
vm_page (using __HAVE_VM_PAGE_MD), rather than a global pv_list head.
- bound check against Sysmap[] in pmap_extract() when asked for a kernel
address.
As a result of this, bsd.rd can now install a working system on a 12MB machine
without needing to enable swap.
