emulation of managed pages. This required the following `interesting' changes:
* File system buffers must be entered with an access type of
VM_PROT_READ|VM_PROT_WRITE, so that the pages will be accessible immediately.
Otherwise we would have to teach pagemove() to update the R/M information.
Since they're never eligible for paging, the latter is overkill.
* We must insure that pages allocated before the pmap is completely set up
(that is, pages allocated early by the VM system) are not eligible for R/M
emulation, since the memory needed for this isn't available. We do this by
allocating the pmap's internal memory with uvm_pageboot_alloc(). This also
fixes an absolutely horrible hack where the pmap only worked because page 0
happened to be mapped.
to be mapped.
Also:
* Push the wired page counting into the p->v list maintenance functions. This
avoids code duplication, and fixes some cases where we were confused about
which pages to do it with.
* Fix lots of problems associated with pmap_nightmare() (and rename it to
pmap_vac_me_harder()).
* Since the early pages are no longer considered `managed', just make
pmap_*_pv() panic if !pmap_initialized.
memory access a mapping was caused by. This is passed through from uvm_fault()
and udv_fault(), and in most other cases is 0.
The pmap module may use this to preset R/M information. On MMUs which require
R/M emulation, the implementation may preset the bits and avoid taking another
fault. On MMUs which keep R/M information in hardware, the implementation may
preset its cached bits to speed up the next call to pmap_is_modified() or
pmap_is_referenced().
clients which have the requested filename fixed in ROM.
The intended echoing behaviour is already provided by the ISC version
(if no special bootfile name is specified in dhcpd.conf).
numerous pagedaemon improvements were needed to make this useful:
- don't bother waking up procs waiting for memory if there's none to be had.
- start 4 times as many pageouts as we need free pages.
this should reduce latency in low-memory situations.
- in inactive scanning, if we find dirty swap-backed pages when swap space
is full of non-resident pages, reactivate some number of these to flush
less active pages to the inactive queue so we can consider paging them out.
this replaces the previous scheme of inactivating pages beyond the
inactive target when we failed to free anything during inactive scanning.
- during both active and inactive scanning, free any swap resources from
dirty swap-backed pages if swap space is full. this allows other pages
be paged out into that swap space.
and ignore the error. Scanset 2 should be the default after reset, so
this allows some broken keyboards to work. (Reset is needed because at
least 1 keyboard locks up if the "set scanset" is attempted.)
disks and CDs, it's just don't have to call DIOCLOCK before, unless we're
doing a forced eject: DIOCEJECT will check for device use and unlock the door
if allowed.
mycroft