pages.
XXX This should be handled better in the future, probably by marking the
XXX page as released, and making uvm_pageunwire() free the page when
XXX the wire count on a released page reaches zero.
* Implement MADV_DONTNEED: deactivate pages in the specified range,
semantics similar to Solaris's MADV_DONTNEED.
* Add MADV_FREE: free pages and swap resources associated with the
specified range, causing the range to be reloaded from backing
store (vnodes) or zero-fill (anonymous), semantics like FreeBSD's
MADV_FREE and like Digital UNIX's MADV_DONTNEED (isn't it SO GREAT
that madvise(2) isn't standardized!?)
As part of this, move the non-map-modifying advice handling out of
uvm_map_advise(), and into sys_madvise().
As another part, implement general amap cleaning in uvm_map_clean(), and
change uvm_map_clean() to only push dirty pages to disk if PGO_CLEANIT
is set in its flags (and update sys___msync13() accordingly). XXX Add
a patchable global "amap_clean_works", defaulting to 1, which can disable
the amap cleaning code, just in case problems are unearthed; this gives
a developer/user a quick way to recover and send a bug report (e.g. boot
into DDB and change the value).
XXX Still need to implement a real uao_flush().
XXX Need to update the manual page.
With these changes, rebuilding libc will automatically cause the new
malloc(3) to use MADV_FREE to actually release pages and swap resources
when it decides that can be done.
the map be at least read-locked to call this function. This requirement
will be taken advantage of in a future commit.
* Write a uvm_fault_unwire() wrapper which read-locks the map and calls
uvm_fault_unwire_locked().
* Update the comments describing the locking contraints of uvm_fault_wire()
and uvm_fault_unwire().
semantics. That is, regardless of the number of mlock/mlockall calls,
an munlock/munlockall actually unlocks the region (i.e. sets wiring count
to 0).
Add a comment describing why uvm_map_pageable() should not be used for
transient page wirings (e.g. for physio) -- note, it's currently only
(ab)used in this way by a few pieces of code which are known to be
broken, i.e. the Amiga and Atari pmaps, and i386 and pc532 if PMAP_NEW is
not used. The i386 GDT code uses uvm_map_pageable(), but in a safe
way, and could be trivially converted to use uvm_fault_wire() instead.
* Provide POSIX 1003.1b mlockall(2) and munlockall(2) system calls.
MCL_CURRENT is presently implemented. MCL_FUTURE is not fully
implemented. Also, the same one-unlock-for-every-lock caveat
currently applies here as it does to mlock(2). This will be
addressed in a future commit.
* Provide the mincore(2) system call, with the same semantics as
Solaris.
* Clean up the error recovery in uvm_map_pageable().
* Fix a bug where a process would hang if attempting to mlock a
zero-fill region where none of the pages in that region are resident.
[ This fix has been submitted for inclusion in 1.4.1 ]
setting recursive has no effect! The kernel lock manager doesn't allow
an exclusive recursion into a shared lock. This situation must simply
be avoided. The only place where this might be a problem is the (ab)use
of uvm_map_pageable() in the Utah-derived pmaps for m68k (they should
either toss the iffy scheme they use completely, or use something like
uvm_fault_wire()).
In addition, once we have looped over uvm_fault_wire(), only upgrade to
an exclusive (write) lock if we need to modify the map again (i.e.
wiring a page failed).
don't unlock a kernel map (!!!) and then relock it later; a recursive lock,
as it used in the user map case, is fine. Also, don't change map entries
while only holding a read lock on the map. Instead, if we fail to wire
a page, clear recursive locking, and upgrade back to a write lock before
dropping the wiring count on the remaining map entries.
locks (and thus, never shared locks). Move the "set/clear recursive"
functions to uvm_map.c, which is the only placed they're used (and
they should go away anyhow). Delete some unused cruft.
right access_type to pass to uvm_fault_wire(). This way, if the entry has
VM_PROT_WRITE, and the entry is marked COW, the copy will happen immediately
in uvm_fault(), as if the access were performed.
has PAGEABLE and INTRSAFE flags. PAGEABLE now really means "pageable",
not "allocate vm_map_entry's from non-static pool", so update all map
creations to reflect that. INTRSAFE maps are maps that are used in
interrupt context (e.g. kmem_map, mb_map), and thus use the static
map entry pool (XXX as does kernel_map, for now). This will eventually
change now these maps are locked, as well.
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.
end of the mappable kernel virtual address space. Previously, it would
get called more often than necessary, because the caller only new what
was requested.
Also, export uvm_maxkaddr so that uvm_pageboot_alloc() can grow the
kernel pmap if necessary, as well. Note that pmap_growkernel() must
now be able to handle being called before pmap_init().
uvmspace_fork().
pmap_fork() is used to "fork a pmap", that is copy data from one pmap
to the other that is NOT related to actual mappings in the pmap, but is
otherwise logically coupled to the address space.
- break anon related functions out of uvm_amap.c and put them in their own
file (uvm_anon.c). includes break up uvm_anon_init into an amap and an
an anon init function
- ensure that only functions within the amap module access amap structure
fields (add macros to amap api as needed)
- replace map checks with submap checks
- get rid of unused 'mainonly' arg in uvm_unmap/uvm_unmap_remove, simplify
code. update all calls to reflect this.
- don't worry about unmapping or changing the protection of shared share
map mappings (is_main_map no longer used).
- remove unused uvm_map_sharemapcopy() function from fork code.
default free list, and 0 - N additional free list, in order of descending
priority.
A new page allocation function, uvm_pagealloc_strat(), has been added,
providing three page allocation strategies:
- normal: high -> low priority free list walk, taking the
page off the first free list that has one.
- only: attempt to allocate a page only from the specified free
list, failing if that free list has none available.
- fallback: if `only' fails, fall back on `normal'.
uvm_pagealloc(...) is provided for normal use (and is a synonym for
uvm_pagealloc_strat(..., UVM_PGA_STRAT_NORMAL, 0); the free list argument
is ignored for the `normal' case).
uvm_page_physload() now specified which free list the pages will be
loaded onto. This means that some platforms which have multiple physical
memory segments may define additional vm_physsegs if they wish to break
individual physical segments into differing priorities.
Machine-dependent code must define _at least_ the following constants
in <machine/vmparam.h>:
VM_NFREELIST: the number of free lists the system will have
VM_FREELIST_DEFAULT: the default freelist (should always be 0,
but is defined in machdep code so that it's with all of the
other free list-related constants).
Additional free list names may be defined by machine-dependent code, but
they will only be used by machine-dependent code (e.g. for loading the
vm_physsegs).
the very rare case of shared mappings that have amap's attached in a
reasonable way -- this is not currently causing any problems, but i
fixed it anyway. update the comment in this section of code and also
be smarter about avoiding needless calls to pmap_protect().
the history buffers are "struct uvm_history_ent" to ensure proper
alignment (eg, alpha). this fixes a boottime panic when the pdhist was
used before it had been initialised.
UVM was written by chuck cranor <chuck@maria.wustl.edu>, with some
minor portions derived from the old Mach code. i provided some help
getting swap and paging working, and other bug fixes/ideas. chuck
silvers <chuq@chuq.com> also provided some other fixes.
this is the UVM kernel code portion.
this will be KNF'd shortly. :-)
thorpej