+/*
+ * Hypercall interface:
+ * Input: %rdi, %rsi, %rdx, %r10, %r8 (arguments 1-5)
+ * Output: %rax
+ * Access is via hypercall page (set up by guest loader or via a Xen MSR):
+ * call hypercall_page + hypercall-number * 32
+ * Clobbered: argument registers (e.g., 2-arg hypercall clobbers %rdi,%rsi)
+ */
+
+#if __XEN_INTERFACE_VERSION__ < 0x00030203
+/*
+ * Legacy hypercall interface:
+ * As above, except the entry sequence to the hypervisor is:
+ * mov $hypercall-number*32,%eax ; syscall
+ * Clobbered: %rcx, %r11, argument registers (as above)
+ */
+#define TRAP_INSTR "syscall"
+#endif
+
+/* Structural guest handles introduced in 0x00030201. */
+#if __XEN_INTERFACE_VERSION__ >= 0x00030201