[FREELOADER]

[reactos.git] / reactos / boot / freeldr / freeldr / arch / i386 / i386disk.c

diff --git a/reactos/boot/freeldr/freeldr/arch/i386/i386disk.c b/reactos/boot/freeldr/freeldr/arch/i386/i386disk.c
index 4bf1d31..bcee453 100644 (file)
--- a/reactos/boot/freeldr/freeldr/arch/i386/i386disk.c
+++ b/reactos/boot/freeldr/freeldr/arch/i386/i386disk.c
@@ -12,9 +12,9 @@
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
- *  You should have received a copy of the GNU General Public License
- *  along with this program; if not, write to the Free Software
- *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #include <freeldr.h>
@@ -51,10 +51,32 @@ BOOLEAN DiskResetController(ULONG DriveNumber)
 
 BOOLEAN DiskInt13ExtensionsSupported(ULONG DriveNumber)
 {
+       static ULONG    LastDriveNumber = 0xffffffff;
+       static BOOLEAN  LastSupported;
        REGS    RegsIn;
        REGS    RegsOut;
 
-       DPRINTM(DPRINT_DISK, "DiskInt13ExtensionsSupported()\n");
+       DPRINTM(DPRINT_DISK, "PcDiskInt13ExtensionsSupported()\n");
+
+       if (DriveNumber == LastDriveNumber)
+       {
+               DPRINTM(DPRINT_DISK, "Using cached value %s for drive 0x%x\n", LastSupported ? "TRUE" : "FALSE", DriveNumber);
+               return LastSupported;
+       }
+
+       // Some BIOSes report that extended disk access functions are not supported
+       // when booting from a CD (e.g. Phoenix BIOS v6.00PG and Insyde BIOS shipping
+       // with Intel Macs). Therefore we just return TRUE if we're booting from a CD -
+       // we can assume that all El Torito capable BIOSes support INT 13 extensions.
+       // We simply detect whether we're booting from CD by checking whether the drive
+       // number is >= 0x8A. It's 0x90 on the Insyde BIOS, and 0x9F on most other BIOSes.
+       if (DriveNumber >= 0x8A)
+       {
+               LastSupported = TRUE;
+               return TRUE;
+       }
+
+       LastDriveNumber = DriveNumber;
 
        // IBM/MS INT 13 Extensions - INSTALLATION CHECK
        // AH = 41h
@@ -90,35 +112,27 @@ BOOLEAN DiskInt13ExtensionsSupported(ULONG DriveNumber)
        if (!INT386_SUCCESS(RegsOut))
        {
                // CF set on error (extensions not supported)
+               LastSupported = FALSE;
                return FALSE;
        }
 
        if (RegsOut.w.bx != 0xAA55)
        {
                // BX = AA55h if installed
+               LastSupported = FALSE;
                return FALSE;
        }
 
-       // Note:
-       // The original check is too strict because some BIOSes report that
-       // extended disk access functions are not suported when booting
-       // from a CD (e.g. Phoenix BIOS v6.00PG). Argh!
-#if 0
        if (!(RegsOut.w.cx & 0x0001))
        {
                // CX = API subset support bitmap
                // Bit 0, extended disk access functions (AH=42h-44h,47h,48h) supported
-               return FALSE;
-       }
-#endif
-
-       // Use this relaxed check instead
-       if (RegsOut.w.cx == 0x0000)
-       {
-               // CX = API subset support bitmap
+               DbgPrint("Suspicious API subset support bitmap 0x%x on device 0x%lx\n", RegsOut.w.cx, DriveNumber);
+               LastSupported = FALSE;
                return FALSE;
        }
 
+       LastSupported = TRUE;
        return TRUE;
 }
 
@@ -135,6 +149,9 @@ BOOLEAN DiskGetExtendedDriveParameters(ULONG DriveNumber, PVOID Buffer, USHORT B
 
        DPRINTM(DPRINT_DISK, "DiskGetExtendedDriveParameters()\n");
 
+       if (!DiskInt13ExtensionsSupported(DriveNumber))
+            return FALSE;
+
        // Initialize transfer buffer
        *Ptr = BufferSize;
 
@@ -163,7 +180,7 @@ BOOLEAN DiskGetExtendedDriveParameters(ULONG DriveNumber, PVOID Buffer, USHORT B
 
        memcpy(Buffer, Ptr, BufferSize);
 
-#ifdef DBG
+#if DBG
     DPRINTM(DPRINT_DISK, "size of buffer:                          %x\n", Ptr[0]);
     DPRINTM(DPRINT_DISK, "information flags:                       %x\n", Ptr[1]);
     DPRINTM(DPRINT_DISK, "number of physical cylinders on drive:   %u\n", *(PULONG)&Ptr[2]);