Re: mipsX_subr.S:tlb_invalid_exception

[David Holland <dholland-mips%netbsd.org@localhost>]

On Sat, Oct 01, 2011 at 11:41:28PM +0900, Masao Uebayashi wrote:
 > - Why load PTE before checking V bit?  If invalid,
 > kern_gen_exception() will load PTE later (uvm_fault() -> pmap_enter()
 > -> tlb_update()), right?

A TLB entry that is present but invalid generates a different flavor
of trap from one that is not present at all. This piece of bodginess
was invented to make the fast-path TLB refill handler shorter.

-- 
David A. Holland
dholland%netbsd.org@localhost