svn commit: r222967 - head/sys/dev/atkbdc

[Xin LI]

Author: delphij
Date: Sat Jun 11 01:19:19 2011
New Revision: 222967
URL: http://svn.freebsd.org/changeset/base/222967

Log:
  Add comments about the validation.

Modified:
  head/sys/dev/atkbdc/atkbd.c

Modified: head/sys/dev/atkbdc/atkbd.c
==============================================================================
--- head/sys/dev/atkbdc/atkbd.c	Sat Jun 11 00:31:37 2011	(r222966)
+++ head/sys/dev/atkbdc/atkbd.c	Sat Jun 11 01:19:19 2011	(r222967)
@@ -1097,6 +1097,15 @@ get_typematic(keyboard_t *kbd)
 	x86regs_t regs;
 	uint8_t *p;
 
+	/*
+	 * Traditional entry points of int 0x15 and 0x16 are fixed
+	 * and later BIOSes follow them.  (U)EFI CSM specification
+	 * also mandate these fixed entry points.
+	 *
+	 * Validate the entry points here before we proceed further.
+	 * It's known that some recent laptops does not have the
+	 * same entry point and hang on boot if we call it.
+	 */
 	if (x86bios_get_intr(0x15) != 0xf000f859 ||
 	    x86bios_get_intr(0x16) != 0xf000e82e)
 		return (ENODEV);