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);
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