managed pages, into KVA space. Since the pages are managed, we should
use pmap_enter(), not pmap_kenter_pa().
Also, when entering the mappings, enter with an access_type of
VM_PROT_READ | VM_PROT_WRITE. We do this for a couple of reasons:
(1) On systems that have H/W mod/ref attributes, the hardware
may not be able to track mod/ref done by a bus master.
(2) On systems that have to do mod/ref emulation, this prevents
a mod/ref page fault from potentially happening while in an
interrupt context, which can be problematic.
This latter change is fairly important if we ever want to be able to
transfer DMA-safe memory pages to anonymous memory objects; we will need
to know that the pages are modified, or else data could be lost!
Note that while the pages are unowned (i.e. "just DMA-safe memory pages"),
they won't consume any swap resources, as the mappings are wired, and
the pages aren't on the active or inactive queues.
which can be used in an interrupt context. Use pmap_kenter*() and
pmap_kremove() only for mappings owned by these objects.
Fixes some locking protocol issues related to MP support, and eliminates
all of the pmap_enter vs. pmap_kremove inconsistencies.
routines now reside in locore.S. No functional difference is expected.
- Replace abused splx() abuse with _splset() to change MIPS processor
interrupt mask bit. 'mips/trap.c' side will be fixed soon.
are still owned by the object which is paging, and so the test for a kernel
object in uvm_unmap_remove() will cause pmap_remove() to be used instead
of pmap_kremove().
This was a MAJOR source of pmap_remove() vs pmap_kremove() inconsistency
(which caused the busted kernel pmap statistics, and a cause of much
locking hair on MP systems).
context, so we must block interrupts which may cause memory allocation
before asserting the kernel pmap's lock. Put this all in PMAP_LOCK()
and PMAP_UNLOCK() macros to make it easier.
level directly, instead of making the caller wrap the calls in
splimp()/splx().
- Add a comment documenting that interrupts that cause memory allocation
must be blocked while the free page queue is locked.
Since interrupts must be blocked while this lock is asserted, tying them
together like this helps to prevent mistakes.
