svn commit: r267928 - stable/10/usr.sbin/bhyve

[John Baldwin]

Author: jhb
Date: Thu Jun 26 19:19:06 2014
New Revision: 267928
URL: http://svnweb.freebsd.org/changeset/base/267928

Log:
  MFC 264277:
  Handle single-byte reads from the bvmcons port (0x220) by returning
  0xff.  Some guests may attempt to read from this port to identify
  psuedo-PNP ISA devices.  (The ie(4) driver in FreeBSD/i386 is one
  example.)

Modified:
  stable/10/usr.sbin/bhyve/consport.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/usr.sbin/bhyve/consport.c
==============================================================================
--- stable/10/usr.sbin/bhyve/consport.c	Thu Jun 26 17:59:23 2014	(r267927)
+++ stable/10/usr.sbin/bhyve/consport.c	Thu Jun 26 19:19:06 2014	(r267928)
@@ -110,6 +110,15 @@ console_handler(struct vmctx *ctx, int v
 		return (0);
 	}
 
+	/*
+	 * Guests might probe this port to look for old ISA devices
+	 * using single-byte reads.  Return 0xff for those.
+	 */
+	if (bytes == 1 && in) {
+		*eax = 0xff;
+		return (0);
+	}
+
 	if (bytes != 4)
 		return (-1);