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diff --git a/vm/vm_object.h b/vm/vm_object.h
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+/*
+ * Copyright (c) 2017 Richard Braun.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Virtual memory object.
+ *
+ * The purpose of VM objects is to track pages that are resident in
+ * physical memory. They collectively form the page cache.
+ */
+
+#ifndef _VM_OBJECT_H
+#define _VM_OBJECT_H
+
+#include <stdint.h>
+
+#include <kern/rdxtree.h>
+#include <vm/vm_object_types.h>
+#include <vm/vm_page.h>
+
+struct vm_object;
+
+/*
+ * Initialize the vm_object module.
+ */
+void vm_object_setup(void);
+
+/*
+ * Initialize a VM object.
+ */
+void vm_object_init(struct vm_object *object, uint64_t size);
+
+/*
+ * Insert a page into a VM object.
+ *
+ * The offset must be page-aligned.
+ *
+ * The page becomes managed, and gains a reference. If successful,
+ * the reference is kept. Otherwise it's dropped. If the page had
+ * no references on entry, and a failure occurs, the page is freed.
+ */
+int vm_object_insert(struct vm_object *object, struct vm_page *page,
+                     uint64_t offset);
+
+/*
+ * Remove pages from a VM object.
+ *
+ * The range boundaries must be page-aligned.
+ *
+ * Holes in the given range are silently skipped. Pages that are removed
+ * become unmanaged and lose a reference.
+ */
+void vm_object_remove(struct vm_object *object, uint64_t start, uint64_t end);
+
+/*
+ * Look up a page in a VM object.
+ *
+ * The offset must be page-aligned.
+ *
+ * If successful, the returned page gains a reference. Note that, if a valid
+ * page is returned, it may already have been removed from the object, or
+ * moved at a different offset.
+ */
+struct vm_page * vm_object_lookup(struct vm_object *object, uint64_t offset);
+
+#endif /* _VM_OBJECT_H */