Index: boot/freeldr/bootsect/isoboot.S
===================================================================
--- boot/freeldr/bootsect/isoboot.S	(revision 74293)
+++ boot/freeldr/bootsect/isoboot.S	(working copy)
@@ -310,10 +310,15 @@
     mov cx, HEX(FFFF)
     call getfssec
 
-    // Fetch our stored drive number to DL and set the boot partition to 0 in DH.
-    mov dl, byte ptr ds:[DriveNumber]
-    mov dh, 0
+    // Pass two parameters to SETUPLDR:
+    //    DL = BIOS Drive Number
+    //    DH = Boot Partition (0 for HDD booting in hybrid mode, FFh for CD booting)
+    movzx dx, byte ptr ds:[DriveNumber]
+    cmp word ptr ds:[GetlinsecPtr], offset getlinsec_ebios
+    je .jump_to_setupldr
+    mov dh, HEX(FF)
 
+.jump_to_setupldr:
     // Transfer execution to the bootloader.
     ljmp16 0, FREELDR_BASE
 
Index: boot/freeldr/freeldr/arch/i386/pcdisk.c
===================================================================
--- boot/freeldr/freeldr/arch/i386/pcdisk.c	(revision 74293)
+++ boot/freeldr/freeldr/arch/i386/pcdisk.c	(working copy)
@@ -575,69 +575,6 @@
     }
 }
 
-
-static BOOLEAN
-FallbackDiskIsCdRomDrive(UCHAR DriveNumber)
-{
-    MASTER_BOOT_RECORD MasterBootRecord;
-
-    TRACE("FallbackDiskIsCdRomDrive(0x%x)\n", DriveNumber);
-
-    /* CD-ROM drive numbers are always > 0x80 */
-    if (DriveNumber <= 0x80)
-        return FALSE;
-
-    /*
-     * We suppose that a CD-ROM does not have a MBR
-     * (not always true: example of the Hybrid USB-ISOs).
-     */
-    return !DiskReadBootRecord(DriveNumber, 0, &MasterBootRecord);
-}
-
-BOOLEAN DiskIsCdRomDrive(UCHAR DriveNumber)
-{
-    REGS RegsIn, RegsOut;
-    PI386_CDROM_SPEC_PACKET Packet = (PI386_CDROM_SPEC_PACKET)(BIOSCALLBUFFER);
-
-    TRACE("DiskIsCdRomDrive(0x%x)\n", DriveNumber);
-
-    /* CD-ROM drive numbers are always > 0x80 */
-    if (DriveNumber <= 0x80)
-        return FALSE;
-
-    /* Setup disk address packet */
-    RtlZeroMemory(Packet, sizeof(*Packet));
-    Packet->PacketSize = sizeof(*Packet);
-
-    /*
-     * BIOS Int 13h, function 4B01h - Bootable CD-ROM - Get Disk Emulation Status
-     * AX = 4B01h
-     * DL = drive number
-     * DS:SI -> empty specification packet
-     * Return:
-     * CF clear if successful
-     * CF set on error
-     * AX = return codes
-     * DS:SI specification packet filled
-     */
-    RegsIn.w.ax = 0x4B01;
-    RegsIn.b.dl = DriveNumber;
-    RegsIn.x.ds = BIOSCALLBUFSEGMENT;   // DS:SI -> specification packet
-    RegsIn.w.si = BIOSCALLBUFOFFSET;
-
-    Int386(0x13, &RegsIn, &RegsOut);
-
-    // return (INT386_SUCCESS(RegsOut) && (Packet->DriveNumber == DriveNumber));
-    /*
-     * If the simple test failed, try to use the fallback code,
-     * but we can be on *very* thin ice.
-     */
-    if (!INT386_SUCCESS(RegsOut) || (Packet->DriveNumber != DriveNumber))
-        return FallbackDiskIsCdRomDrive(DriveNumber);
-    else
-        return TRUE;
-}
-
 BOOLEAN
 PcDiskGetBootPath(OUT PCHAR BootPath, IN ULONG Size)
 {
Index: boot/freeldr/freeldr/disk/disk.c
===================================================================
--- boot/freeldr/freeldr/disk/disk.c	(revision 74293)
+++ boot/freeldr/freeldr/disk/disk.c	(working copy)
@@ -100,10 +100,6 @@
     return TRUE;
 }
 
-
-extern BOOLEAN
-DiskIsCdRomDrive(UCHAR DriveNumber);
-
 BOOLEAN DiskGetBootPath(OUT PCHAR BootPath, IN ULONG Size)
 {
     if (*FrldrBootPath)
@@ -121,9 +117,9 @@
         /* This is a floppy */
         sprintf(FrldrBootPath, "multi(0)disk(0)fdisk(%u)", FrldrBootDrive);
     }
-    else if (DiskIsCdRomDrive(FrldrBootDrive))
+    else if (FrldrBootPartition == 0xFF)
     {
-        /* This is a CD-ROM drive */
+        /* Boot Partition 0xFF is the magic value that indicates booting from CD-ROM (see isoboot.S) */
         sprintf(FrldrBootPath, "multi(0)disk(0)cdrom(%u)", FrldrBootDrive - 0x80);
     }
     else