Implement COW pages! :^)

sys$fork() now clones all writable regions with per-page COW bits.
The pages are then mapped read-only and we handle a PF by COWing the pages.

This is quite delightful. Obviously there's lots of work to do still,
and it needs better data structures, but the general concept works.

1 files changed, 5 insertions, 0 deletions

diff --git a/Kernel/types.h b/Kernel/types.h
index 8a61b405a5..4fd1375ef0 100644
--- a/Kernel/types.h
+++ b/Kernel/types.h
@@ -105,3 +105,8 @@ public:
 private:
     dword m_address { 0 };
 };
+
+inline LinearAddress operator-(const LinearAddress& a, const LinearAddress& b)
+{
+    return LinearAddress(a.get() - b.get());
+}