[isa] Disable legacy ISA device probing by default

Legacy ISA device probing involves poking at various I/O addresses to
guess whether or not a particular device is present.

Actual legacy ISA cards are essentially nonexistent by now, but the
probed I/O addresses have a habit of being reused for various
OEM-specific functions.  This can cause some very undesirable side
effects.  For example, probing for the "ne2k_isa" driver on an HP
Elitebook 840 G10 will cause the system to lock up in a way that
requires two cold reboots to recover.

Enable ISA_PROBE_ONLY in config/isa.h by default.  This limits ISA
probing to use only the addresses specified in ISA_PROBE_ADDRS, which
is empty by default, and so effectively disables ISA probing.  The
vanishingly small number of users who require ISA probing can simply
adjust this configuration in config/local/isa.h.

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

diff --git a/src/config/isa.h b/src/config/isa.h
index e2a05050f3d55d83c399ae38f20d598aa71848b3..dce9c9b48b7421e5ca59560b48cfdea74fccbf20 100644 (file)
--- a/src/config/isa.h
+++ b/src/config/isa.h
@@ -10,7 +10,7 @@
  *
  */
 #undef ISA_PROBE_ADDRS         /* e.g. 0x200, 0x300 */
-#undef ISA_PROBE_ONLY          /* Do not probe any other addresses */
+#define        ISA_PROBE_ONLY          /* Do not probe any other addresses */
 
 #include <config/local/isa.h>