distinct and allowing this makes certain useful tasks possible, such as
fixing an unpopulated /dev while a tmpfs is mounted over it.
However, require the paths to be different, as mounting a path directly over
itself has the side effect of causing any other mount points within that path
to no longer be accessible, and is difficult to unmount when done on /.
The change also prevents arp_dad_timer/nd6_dad_timer from running if
arp_dad_stop/nd6_dad_stop is called, which makes sure that callout_reset
won't be called during callout_halt.
1) invesion of enable bits in splx (ipl_sr_map is disable mask)
2) Don't overwrite the cause register in spl0 - there might be pending
softints.
The second helps with recent boot issues after several new workqueues
are created. lwp_startup would call spl0 and lose the pending softints
status.
the CPU crashes right after waking up, since it needs to access NOX-ed
pages, which are to be enabled in an MSR.
Fix this by properly saving and restoring the EFER MSR. It's a little
tricky since the wakeup code uses %edx, but rdmsr overwrites it. We just
save it in %esi.
Now, the CPU sleeps properly on PAE kernels.
rather than just ignoring the error.
Don't bother attempting to clear the contents of /var/run if /var/run
does not exist.
In that case the mkdir of /var/run/lvm would have failed - correct that
by using mkdir -p (which as a side effect will ensure /var/run exists
and is available for later scripts to use if for some reason it did not exist.)
the page tree so that the first 2MB of virtual memory can be kentered in
L1.
Strictly speaking, the kernel should never kenter a virtual page below
VM_MIN_KERNEL_ADDRESS, because then it wouldn't be available in userland.
It used to need the first 2MB in order to map the CPU trampoline and the
initial VAs used by the bootstrap code. Now, the CPU trampoline VA is
allocated with uvm_km_alloc and the VAs used by the bootstrap code are
allocated with pmap_bootstrap_valloc, and in either case the resulting VA
is above VM_MIN_KERNEL_ADDRESS.
The low levels in the page tree are therefore unused. By removing this
function, we are making sure no one will be tempted to map an area below
VM_MIN_KERNEL_ADDRESS in kernel mode, and particularly, we are making sure
NULL cannot be kentered.
In short, there is no way to map NULL in kernel mode anymore.
