+#ifdef CONFIG_USER_ONLY
+/* ??? The kernel likes to give addresses in high memory. If the host has
+ more virtual address space than the guest, this can lead to impossible
+ allocations. Honor the long-standing assumption that only kernel addrs
+ are negative, but otherwise allow allocations anywhere. This could lead
+ to tricky emulation problems for programs doing tagged addressing, but
+ that's far fewer than encounter the impossible allocation problem. */
+#define TARGET_PHYS_ADDR_SPACE_BITS 63
+#define TARGET_VIRT_ADDR_SPACE_BITS 63
+#else