--- arch/xen/i386/kernel/process.c.orig	2005-02-12 03:39:44.000000000 +0000
+++ arch/xen/i386/kernel/process.c	2005-02-13 02:46:03.000000000 +0000
@@ -563,6 +563,14 @@
 	if (prev_p->thread_info->status & TS_USEDFPU) {
 		save_init_fpu(prev_p);
 		queue_multicall0(__HYPERVISOR_fpu_taskswitch);
+	} else {
+		short msw;
+		asm ("smsw %[msw]" : [msw] "=g"(msw));
+		if (!(msw & 8)) {
+			signed short fenv[14];
+			asm ("fstenv %[fenv]" : [fenv] "=g"(fenv));
+			if (fenv [4] != -1) panic ("corrupt FPU");
+		}
 	}
 
 	/*