Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE

David Mosberger
2004-05-25T04:43:00Z

>>>>> On Tue, 25 May 2004 06:20:54 +0200, Andrea Arcangeli <andrea@suse.de> said:

Andrea> the only architecture that has the accessed bit in
Andrea> _hardware_ via page faults I know is ia64, but I don't know
Andrea> if it has a mode to set it without page faults

No, it doesn't.

Andrea> and how it is implementing the accessed bit in linux.

If the "accessed" or "dirty" bits are zero, accessing/writing the
page will cause a fault which will be handled in a low-level
fault handler. The Linux version of these handlers simply turn
on the respective bit. See daccess_bit(), iaccess_bit(), and dirty_bit()
in arch/ia64/kernel/ivt.S.

Note: I'm on travel and haven't seen the context of this discussion
and don't expect to have time to think about this until I return on
Thursday. So if you don't hear from me, it's not because I'm ignoring
you... ;-)

--david