For FreeBSD 4 binaries, when trying to read from a device that does

not exsist, do not have ioctl return an error, but instead set -1
in the data returned to the user.  This allows the HP bios flash
utilities to work without requiring changes to their code.

Reviewed by:	jhb

sys/dev/pci/pci_user.c

@@ -28,6 +28,7 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_bus.h"	/* XXX trim includes */
+#include "opt_compat.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -411,7 +412,13 @@ pci_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag, struct thread *t
 							  io->pi_width);
 				error = 0;
 			} else {
-				error = ENODEV;
+#ifdef COMPAT_FREEBSD4
+				if (cmd == PCIOCREAD) {
+					io->pi_data = -1;
+					error = 0;
+				} else
+#endif
+					error = ENODEV;
 			}
 			break;
 		default: