[int13] Add support for INT 13,4b

This allows the ELTORITO.SYS driver for MS-DOS to access our emulated
CD-ROM drives.

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

diff --git a/src/arch/i386/interface/pcbios/int13.c b/src/arch/i386/interface/pcbios/int13.c
index 3af3652e0cac061bc961fb3cdcdf0475d29d0cb5..93d01088fae289d250e6202418e383245a17afb2 100644 (file)
--- a/src/arch/i386/interface/pcbios/int13.c
+++ b/src/arch/i386/interface/pcbios/int13.c
@@ -124,6 +124,8 @@ struct int13_drive {
         */
        unsigned int sectors_per_track;
 
+       /** Drive is a CD-ROM */
+       int is_cdrom;
        /** Address of El Torito boot catalog (if any) */
        unsigned int boot_catalog;
 
@@ -468,6 +470,7 @@ static int int13_parse_iso9660 ( struct int13_drive *int13, void *scratch ) {
                return 0;
        DBGC ( int13, "INT13 drive %02x contains an ISO9660 filesystem; "
               "treating as CD-ROM\n", int13->drive );
+       int13->is_cdrom = 1;
 
        /* Read boot record volume descriptor */
        if ( ( rc = int13_rw ( int13,
@@ -1090,6 +1093,41 @@ static int int13_get_extended_parameters ( struct int13_drive *int13,
        return 0;
 }
 
+/**
+ * INT 13, 4b - Get status or terminate CD-ROM emulation
+ *
+ * @v int13            Emulated drive
+ * @v ds:si            Specification packet
+ * @ret status         Status code
+ */
+static int int13_cdrom_status_terminate ( struct int13_drive *int13,
+                                         struct i386_all_regs *ix86 ) {
+       struct int13_cdrom_specification specification;
+
+       DBGC2 ( int13, "Get CD-ROM emulation status to %04x:%04x%s\n",
+               ix86->segs.ds, ix86->regs.si,
+               ( ix86->regs.al ? "" : " and terminate" ) );
+
+       /* Fail if we are not a CD-ROM */
+       if ( ! int13->is_cdrom ) {
+               DBGC ( int13, "INT13 drive %02x is not a CD-ROM\n",
+                      int13->drive );
+               return -INT13_STATUS_INVALID;
+       }
+
+       /* Build specification packet */
+       memset ( &specification, 0, sizeof ( specification ) );
+       specification.size = sizeof ( specification );
+       specification.drive = int13->drive;
+
+       /* Return specification packet */
+       copy_to_real ( ix86->segs.ds, ix86->regs.si, &specification,
+                      sizeof ( specification ) );
+
+       return 0;
+}
+
+
 /**
  * INT 13, 4d - Read CD-ROM boot catalog
  *
@@ -1102,6 +1140,11 @@ static int int13_cdrom_read_boot_catalog ( struct int13_drive *int13,
        struct int13_cdrom_boot_catalog_command command;
        int rc;
 
+       /* Read parameters from command packet */
+       copy_from_real ( &command, ix86->segs.ds, ix86->regs.si,
+                        sizeof ( command ) );
+       DBGC2 ( int13, "Read CD-ROM boot catalog to %08x\n", command.buffer );
+
        /* Fail if we have no boot catalog */
        if ( ! int13->boot_catalog ) {
                DBGC ( int13, "INT13 drive %02x has no boot catalog\n",
@@ -1109,10 +1152,6 @@ static int int13_cdrom_read_boot_catalog ( struct int13_drive *int13,
                return -INT13_STATUS_INVALID;
        }
 
-       /* Read parameters from command packet */
-       copy_from_real ( &command, ix86->segs.ds, ix86->regs.si,
-                        sizeof ( command ) );
-
        /* Read from boot catalog */
        if ( ( rc = int13_rw ( int13, ( int13->boot_catalog + command.start ),
                               command.count, phys_to_user ( command.buffer ),
@@ -1192,6 +1231,9 @@ static __asmcall void int13 ( struct i386_all_regs *ix86 ) {
                case INT13_GET_EXTENDED_PARAMETERS:
                        status = int13_get_extended_parameters ( int13, ix86 );
                        break;
+               case INT13_CDROM_STATUS_TERMINATE:
+                       status = int13_cdrom_status_terminate ( int13, ix86 );
+                       break;
                case INT13_CDROM_READ_BOOT_CATALOG:
                        status = int13_cdrom_read_boot_catalog ( int13, ix86 );
                        break;