vm/vm_kmem: check that kernel space doesn't start at 0

Address 0 is commonly used to report allocation errors, in particular to
the kmem module, which itself returns NULL on failure.

1 files changed, 8 insertions, 0 deletions

diff --git a/vm/vm_kmem.h b/vm/vm_kmem.h
index feaf0b16..f2296ec3 100644
--- a/vm/vm_kmem.h
+++ b/vm/vm_kmem.h
@@ -21,6 +21,14 @@
 #include <kern/types.h>
 
 /*
+ * The kernel space is required not to start at address 0, which is used to
+ * report allocation errors.
+ */
+#if VM_MIN_KERNEL_ADDRESS == 0
+#error "kernel space must not start at address 0"
+#endif
+
+/*
  * Special kernel addresses.
  */
 extern char _text;