diff --git a/libs/libvmbase/src/layout/crosvm.rs b/libs/libvmbase/src/layout/crosvm.rs
index d859b20..39a8147 100644
--- a/libs/libvmbase/src/layout/crosvm.rs
+++ b/libs/libvmbase/src/layout/crosvm.rs
@@ -21,10 +21,13 @@
 /// The start address of MMIO space.
 pub const MMIO_START: usize = 0x0;
 /// The end address of MMIO space.
-pub const MMIO_END: usize = 0x4000_0000;
+pub const MMIO_END: usize = PVMFW_START;
 /// MMIO range.
 pub const MMIO_RANGE: Range<usize> = MMIO_START..MMIO_END;
 
+/// Start pvmfw region.
+pub const PVMFW_START: usize = 0x7fc00000;
+
 /// The start of the system's contiguous "main" memory.
 pub const MEM_START: usize = 0x8000_0000;