The default template argument is only used in one place, and it
looks like it was probably just an oversight. The rest of the Kernel
code all uses u8 as the type. So lets make that the default and remove
the unused template argument, as there doesn't seem to be a reason to
allow the size to be customizable.
The VMObject class now manages its own instance list (it was previously
a member of MemoryManager.) Removal from the list is done safely on the
last unref(), closing a race window in the previous implementation.
Note that VMObject::all_instances() now has its own lock instead of
using the global MM lock.
When booting AP's, we identity map a region at 0x8000 while doing the
initial bringup sequence. This is the only thing in the kernel that
requires an identity mapping, yet we had a bunch of generic API's and a
dedicated VirtualRangeAllocator in every PageDirectory for this purpose.
This patch simplifies the situation by moving the identity mapping logic
to the AP boot code and removing the generic API's.
...and also RangeAllocator => VirtualRangeAllocator.
This clarifies that the ranges we're dealing with are *virtual* memory
ranges and not anything else.
