[fdtmem] Allow iPXE to be relocated to the top of the address space

Allow for relocation to a region at the very end of the physical
address space (where the next address wraps to zero).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/core/fdtmem.c b/src/core/fdtmem.c
index b357287c5ce38b183cef1898cdd50f53e5caffb5..ef1ceb59df30be0caaca04af5bcbb456dc2cdf10 100644 (file)
--- a/src/core/fdtmem.c
+++ b/src/core/fdtmem.c
@@ -300,7 +300,8 @@ physaddr_t fdtmem_relocate ( struct fdt_header *hdr, physaddr_t max ) {
                assert ( region.last >= region.addr );
 
                /* Use highest possible region */
-               if ( memmap_is_usable ( &region ) && ( next >= len ) ) {
+               if ( memmap_is_usable ( &region ) &&
+                    ( ( next == 0 ) || ( next >= len ) ) ) {
 
                        /* Determine candidate address after alignment */
                        try = ( ( next - len ) & ~( max_align - 1 ) );