a HAVE_GCC28 check-variable that can now be used to add other gcc-2.8
flags in cases where they may be useful, or to remove gcc 2.7.2 "bug
workaround" flags.)
- Maintain two copies of the number and size of physical memory segments.
One copy, mem_clusters[], contains _all_ of physical RAM, for crash dumps.
The other copy, phys_seg_list[], starts out with all of physical RAM (and
is used to initialize mem_clusters[]), but is adjusted to be the memory
actually managed by the VM system.
- Fix computation of physmem; when support for MACHINE_NEW_NONCONTIG was
added, physmem was accidentally changed to not take into account the memory
located before the kernel, or the memory taken up by the kernel itself.
- Make initialization of the message buffer a little less magic-looking.
- Maintain two copies of the number and size of physical memory segments.
One copy, mem_clusters[], contains _all_ of physical RAM, for crash dumps.
The other copy, phys_seg_list[], starts out with all of physical RAM (and
is used to initialize mem_clusters[]), but is adjusted to be the memory
actually managed by the VM system.
- Fix crash dumps with regard to multiple memory segments.
as this breaks C++ code that happens to indirectly include this header.
Both Matthias Scheler and I noticed this, independently.
This problem notably does not affect the atari and sun3/sun3x ports,
which have already implemented a similar solution.
was converted to use Mach VM for Net2/4.4BSD. The user segment table
pointer was originally stored in the PCB. When Mach VM came along,
however, it was also stored in the pmap, and loaded into the PCB in
pmap_activate(). pmap_activate() would then note that the PCB's USTP
was now in sync with the pmap's USTP, and the low-level context switch
code would use the value from the PCB.
However, pmap_activate() would also load the hardware MMU context if
the pmap was the current pmap (or, in the case where pmaps can be shared,
such as in NetBSD, if the proc was the current proc). The low-level
context switch code would then reload the hardware _again_ using the
USTP from the PCB.
However, the optimization of not calling pmap_activate() if "stchanged"
was false ended up causing some processes to use stale USTP values from
the PCB when the low-level context switch code reloaded the hardware!
This was noticed by using a real vfork(2) (which worked for some time
before failing, surprisingly!)
Since I'm hard pressed to find any real optimization here (since the
hardware was always reloaded once, sometimes twice!), the code now always
calls pmap_activate(), which uses the correct USTP value (the one in the
pmap). The PCB's USTP is now ignored, and should eventually be g/c'd.
Another optimization can actually be performed, and I have added a comment
describing what it is, but have not yet implemented it.
Also note that most of the loadustp() functions where actually incomplete.
This has been corrected. These functions should probably be split up into
MMU-specific operations, and called indirectly, rather than doing constant
run-time decision making based on values that will never change during the
course of a boot's lifetime.
