feat: implement capability-based memory management foundation

kernel/src/mem/pm_manages.rs

@@ -0,0 +1,25 @@
+use crate::cap::{Capability, CapObject, Relation, CapRights};
+use crate::mem::address::PhysAddr;
+
+pub struct PMActor {
+    pub root_untyped: Capability,
+    pub managed_range: (PhysAddr, PhysAddr),
+}
+
+impl PMActor {
+    pub fn carve_region(&self, offset: usize, size: usize) -> Capability {
+        if let CapObject::Memory { phys, .. } = self.root_untyped.object {
+            Capability {
+                object: CapObject::Memory {
+                    phys: PhysAddr(phys.0 + offset as u64),
+                    size_pages: size / 4096,
+                },
+                rights: CapRights::READ | CapRights::WRITE | CapRights::GRANT,
+                relation: Relation::Strong,
+                token_sig: 0xDEAD_BEEF,
+            }
+        } else {
+            panic!("PM: Root is not memory!");
+        }
+    }
+}