Trying to get a CDROM working under gentoo.  It worked just before I installed gentoo in Ubuntu,
but I didn't use a CDROM install for gentoo, so it's probably just some arcane bit of
configuration.  ATAPI support (for CD-ROM) is enabled in the kernel.  There is a disc in the drive
and it isn't an oreo or an audio CD, it's a data disc.  The CD works under windows and as I said,
the drive worked in ubuntu just before I installed.  I've tried TLDP's CDROM-HOWTO and nothing
there helped.

Here are the results of commands in console:

 # mount -t iso9660 /dev/cdrom /mnt/cdrom
mount: No medium found

 # mount -t iso9660 /dev/hdc /mnt/cdrom
mount: No medium found

(same responses above after making changing fstab line to:
/dev/cdrom      /mnt/cdrom      iso9660         noauto,user     0 0

 # lspci 
00:02.5 IDE interface: Silicon Integrated Systems [SiS] 5513 [IDE]
(relevant because that is the specific IDE interface enabled in the kernel)

 # dmesg | grep CD
hdc: LITE-ON LTR-40125S, ATAPI CD/DVD-ROM drive
hdc: ATAPI 48X CD-ROM CD-R/RW drive, 1984kB Cache, UDMA(33)
Uniform CD-ROM driver Revision: 3.20

 # dmesg | grep hdc
    ide1: BM-DMA at 0x4008-0x400f, BIOS settings: hdc:DMA, hdd:pio
hdc: LITE-ON LTR-40125S, ATAPI CD/DVD-ROM drive
hdc: ATAPI 48X CD-ROM CD-R/RW drive, 1984kB Cache, UDMA(33)
hdc: lost interrupt
hdc: CHECK for good STATUS

 # hdparm -i /dev/hdc

/dev/hdc:

 Model=LITE-ON LTR-40125S, FwRev=ZS0G, SerialNo=
 Config={ Fixed Removeable DTR<=5Mbs DTR>10Mbs nonMagnetic }
 RawCHS=0/0/0, TrkSize=0, SectSize=0, ECCbytes=0
 BuffType=unknown, BuffSize=0kB, MaxMultSect=0
 (maybe): CurCHS=0/0/0, CurSects=0, LBA=yes, LBAsects=0
 IORDY=yes, tPIO={min:227,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio1 pio2 pio3 pio4 
 DMA modes:  mdma0 mdma1 mdma2 
 UDMA modes: udma0 udma1 *udma2 
 AdvancedPM=no

 * signifies the current active mode

 # hdparm /dev/hdc

/dev/hdc:
 IO_support   =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    = 256 (on)
 HDIO_GETGEO failed: Invalid argument

 # ls /dev/hd*
/dev/hda  /dev/hda1  /dev/hda2  /dev/hda3  /dev/hda5  /dev/hda6  /dev/hdc

 # ls /dev/cd*
/dev/cdrom  /dev/cdrw

 # file /dev/cdrw
/dev/cdrw: symbolic link to `hdc'

 # file /dev/cdrom
/dev/cdrom: symbolic link to `hdc'
 # mount -t iso9660 /dev/hdc /mnt/cdrom
mount: No medium found

 # cat /etc/fstab | grep -v \# | sed -e '/^$/d'
/dev/hda1               /boot           ext2            defaults,noatime1 2
/dev/hda2               none            swap            sw              0 0
/dev/hda5               /               reiserfs        noatime         0 1
/dev/hdc      /mnt/cdrom        iso9660         auto,user       0 0
none                    /proc           proc            defaults        0 0
none                    /dev/shm        tmpfs           nodev,nosuid,noexec0 0
//Mpu/dis       /mnt/dis    smbfs       guest       0 0

The rest is the .config file for the current kernel I'm using it's very boring but here it is:
 # cat /usr/src/linux/.config | grep -v \# | sed -e '/^$/d'
CONFIG_X86=y
CONFIG_SEMAPHORE_SLEEPERS=y
CONFIG_MMU=y
CONFIG_UID16=y
CONFIG_GENERIC_ISA_DMA=y
CONFIG_GENERIC_IOMAP=y
CONFIG_ARCH_MAY_HAVE_PC_FDC=y
CONFIG_EXPERIMENTAL=y
CONFIG_CLEAN_COMPILE=y
CONFIG_LOCK_KERNEL=y
CONFIG_INIT_ENV_ARG_LIMIT=32
CONFIG_LOCALVERSION=""
CONFIG_LOCALVERSION_AUTO=y
CONFIG_SWAP=y
CONFIG_SYSVIPC=y
CONFIG_POSIX_MQUEUE=y
CONFIG_SYSCTL=y
CONFIG_AUDIT=y
CONFIG_AUDITSYSCALL=y
CONFIG_HOTPLUG=y
CONFIG_KOBJECT_UEVENT=y
CONFIG_INITRAMFS_SOURCE=""
CONFIG_KALLSYMS=y
CONFIG_PRINTK=y
CONFIG_BUG=y
CONFIG_BASE_FULL=y
CONFIG_FUTEX=y
CONFIG_EPOLL=y
CONFIG_SHMEM=y
CONFIG_CC_ALIGN_FUNCTIONS=0
CONFIG_CC_ALIGN_LABELS=0
CONFIG_CC_ALIGN_LOOPS=0
CONFIG_CC_ALIGN_JUMPS=0
CONFIG_BASE_SMALL=0
CONFIG_MODULES=y
CONFIG_MODULE_UNLOAD=y
CONFIG_OBSOLETE_MODPARM=y
CONFIG_KMOD=y
CONFIG_STOP_MACHINE=y
CONFIG_X86_PC=y
CONFIG_MPENTIUM4=y
CONFIG_X86_CMPXCHG=y
CONFIG_X86_XADD=y
CONFIG_X86_L1_CACHE_SHIFT=7
CONFIG_RWSEM_XCHGADD_ALGORITHM=y
CONFIG_GENERIC_CALIBRATE_DELAY=y
CONFIG_X86_WP_WORKS_OK=y
CONFIG_X86_INVLPG=y
CONFIG_X86_BSWAP=y
CONFIG_X86_POPAD_OK=y
CONFIG_X86_GOOD_APIC=y
CONFIG_X86_INTEL_USERCOPY=y
CONFIG_X86_USE_PPRO_CHECKSUM=y
CONFIG_SMP=y
CONFIG_NR_CPUS=8
CONFIG_SCHED_SMT=y
CONFIG_PREEMPT=y
CONFIG_PREEMPT_BKL=y
CONFIG_X86_LOCAL_APIC=y
CONFIG_X86_IO_APIC=y
CONFIG_X86_TSC=y
CONFIG_X86_MCE=y
CONFIG_X86_MCE_NONFATAL=y
CONFIG_X86_MCE_P4THERMAL=y
CONFIG_DCDBAS=m
CONFIG_NOHIGHMEM=y
CONFIG_SELECT_MEMORY_MODEL=y
CONFIG_FLATMEM_MANUAL=y
CONFIG_FLATMEM=y
CONFIG_FLAT_NODE_MEM_MAP=y
CONFIG_MTRR=y
CONFIG_IRQBALANCE=y
CONFIG_SECCOMP=y
CONFIG_HZ_250=y
CONFIG_HZ=250
CONFIG_PHYSICAL_START=0x100000
CONFIG_PM=y
CONFIG_APM=y
CONFIG_PCI=y
CONFIG_PCI_GOANY=y
CONFIG_PCI_BIOS=y
CONFIG_PCI_DIRECT=y
CONFIG_PCI_LEGACY_PROC=y
CONFIG_ISA_DMA_API=y
CONFIG_ISA=y
CONFIG_BINFMT_ELF=y
CONFIG_BINFMT_AOUT=y
CONFIG_BINFMT_MISC=y
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_PACKET_MMAP=y
CONFIG_UNIX=y
CONFIG_XFRM=y
CONFIG_NET_KEY=y
CONFIG_INET=y
CONFIG_IP_MULTICAST=y
CONFIG_IP_FIB_HASH=y
CONFIG_INET_DIAG=y
CONFIG_INET_TCP_DIAG=y
CONFIG_TCP_CONG_BIC=y
CONFIG_IPV6=m
CONFIG_NETFILTER=y
CONFIG_IP_NF_CONNTRACK=y
CONFIG_IP_NF_QUEUE=y
CONFIG_IP_NF_IPTABLES=y
CONFIG_IP_NF_MATCH_LIMIT=y
CONFIG_IP_NF_MATCH_IPRANGE=y
CONFIG_IP_NF_MATCH_MAC=y
CONFIG_IP_NF_MATCH_PKTTYPE=y
CONFIG_IP_NF_MATCH_MARK=y
CONFIG_IP_NF_MATCH_MULTIPORT=y
CONFIG_IP_NF_MATCH_TOS=y
CONFIG_IP_NF_MATCH_RECENT=y
CONFIG_IP_NF_MATCH_ECN=y
CONFIG_IP_NF_MATCH_DSCP=y
CONFIG_IP_NF_MATCH_AH_ESP=y
CONFIG_IP_NF_MATCH_LENGTH=y
CONFIG_IP_NF_MATCH_TTL=y
CONFIG_IP_NF_MATCH_TCPMSS=y
CONFIG_IP_NF_MATCH_HELPER=y
CONFIG_IP_NF_MATCH_STATE=y
CONFIG_IP_NF_MATCH_CONNTRACK=y
CONFIG_IP_NF_MATCH_OWNER=y
CONFIG_IP_NF_FILTER=y
CONFIG_IP_NF_TARGET_REJECT=y
CONFIG_IP_NF_TARGET_LOG=y
CONFIG_IP_NF_TARGET_ULOG=y
CONFIG_IP_NF_TARGET_TCPMSS=y
CONFIG_IP_NF_NAT=y
CONFIG_IP_NF_NAT_NEEDED=y
CONFIG_IP_NF_TARGET_MASQUERADE=y
CONFIG_IP_NF_TARGET_REDIRECT=y
CONFIG_IP_NF_TARGET_NETMAP=y
CONFIG_IP_NF_TARGET_SAME=y
CONFIG_IP_NF_MANGLE=y
CONFIG_IP_NF_TARGET_TOS=y
CONFIG_IP_NF_TARGET_ECN=y
CONFIG_IP_NF_TARGET_DSCP=y
CONFIG_IP_NF_TARGET_MARK=y
CONFIG_IP_NF_TARGET_CLASSIFY=y
CONFIG_IP_NF_RAW=m
CONFIG_IP_NF_TARGET_NOTRACK=m
CONFIG_IP_NF_ARPTABLES=y
CONFIG_IP_NF_ARPFILTER=y
CONFIG_IP_NF_ARP_MANGLE=y
CONFIG_STANDALONE=y
CONFIG_PREVENT_FIRMWARE_BUILD=y
CONFIG_FW_LOADER=m
CONFIG_PARPORT=y
CONFIG_PARPORT_PC=y
CONFIG_PNP=y
CONFIG_PNPBIOS=y
CONFIG_BLK_DEV_FD=y
CONFIG_BLK_DEV_RAM_COUNT=16
CONFIG_LBD=y
CONFIG_IOSCHED_NOOP=y
CONFIG_IOSCHED_AS=y
CONFIG_IOSCHED_DEADLINE=y
CONFIG_IOSCHED_CFQ=y
CONFIG_IDE=y
CONFIG_BLK_DEV_IDE=y
CONFIG_BLK_DEV_IDEDISK=y
CONFIG_IDEDISK_MULTI_MODE=y
CONFIG_BLK_DEV_IDECD=y
CONFIG_IDE_GENERIC=y
CONFIG_BLK_DEV_CMD640=y
CONFIG_BLK_DEV_IDEPCI=y
CONFIG_IDEPCI_SHARE_IRQ=y
CONFIG_BLK_DEV_GENERIC=y
CONFIG_BLK_DEV_RZ1000=y
CONFIG_BLK_DEV_IDEDMA_PCI=y
CONFIG_IDEDMA_PCI_AUTO=y
CONFIG_BLK_DEV_SIS5513=y
CONFIG_BLK_DEV_IDEDMA=y
CONFIG_IDEDMA_AUTO=y
CONFIG_SCSI=y
CONFIG_SCSI_PROC_FS=y
CONFIG_BLK_DEV_SD=y
CONFIG_CHR_DEV_SG=y
CONFIG_SCSI_DPT_I2O=m
CONFIG_SCSI_SATA=y
CONFIG_SCSI_ATA_PIIX=y
CONFIG_SCSI_SATA_SX4=m
CONFIG_SCSI_SATA_SIS=m
CONFIG_SCSI_SATA_INTEL_COMBINED=y
CONFIG_SCSI_IPR=m
CONFIG_SCSI_QLA2XXX=y
CONFIG_IEEE1394=m
CONFIG_NETDEVICES=y
CONFIG_DUMMY=m
CONFIG_NET_ETHERNET=y
CONFIG_MII=y
CONFIG_NET_PCI=y
CONFIG_8139TOO=y
CONFIG_8139TOO_PIO=y
CONFIG_SIS900=y
CONFIG_S2IO=m
CONFIG_INPUT=y
CONFIG_INPUT_MOUSEDEV=y
CONFIG_INPUT_MOUSEDEV_PSAUX=y
CONFIG_INPUT_MOUSEDEV_SCREEN_X=1280
CONFIG_INPUT_MOUSEDEV_SCREEN_Y=1024
CONFIG_INPUT_KEYBOARD=y
CONFIG_KEYBOARD_ATKBD=y
CONFIG_INPUT_MOUSE=y
CONFIG_MOUSE_PS2=y
CONFIG_INPUT_MISC=y
CONFIG_SERIO=y
CONFIG_SERIO_I8042=y
CONFIG_SERIO_LIBPS2=y
CONFIG_VT=y
CONFIG_VT_CONSOLE=y
CONFIG_HW_CONSOLE=y
CONFIG_SERIAL_8250=y
CONFIG_SERIAL_8250_NR_UARTS=4
CONFIG_SERIAL_CORE=y
CONFIG_UNIX98_PTYS=y
CONFIG_LEGACY_PTYS=y
CONFIG_LEGACY_PTY_COUNT=256
CONFIG_AGP=y
CONFIG_AGP_INTEL=y
CONFIG_AGP_SIS=y
CONFIG_I2C=y
CONFIG_I2C_ALGOBIT=y
CONFIG_HWMON=y
CONFIG_FB=y
CONFIG_FB_CFB_FILLRECT=y
CONFIG_FB_CFB_COPYAREA=y
CONFIG_FB_CFB_IMAGEBLIT=y
CONFIG_FB_SOFT_CURSOR=y
CONFIG_FB_MODE_HELPERS=y
CONFIG_FB_VESA=y
CONFIG_FB_VESA_TNG=y
CONFIG_FB_VESA_DEFAULT_MODE="1280x1024@75"
CONFIG_VIDEO_SELECT=y
CONFIG_FB_RADEON=y
CONFIG_FB_RADEON_I2C=y
CONFIG_VGA_CONSOLE=y
CONFIG_DUMMY_CONSOLE=y
CONFIG_FRAMEBUFFER_CONSOLE=y
CONFIG_FONTS=y
CONFIG_FONT_SUN8x16=y
CONFIG_LOGO=y
CONFIG_LOGO_LINUX_CLUT224=y
CONFIG_FB_SPLASH=y
CONFIG_SPEAKUP_DEFAULT="none"
CONFIG_SOUND=y
CONFIG_SND=y
CONFIG_SND_TIMER=y
CONFIG_SND_PCM=y
CONFIG_SND_SEQUENCER=y
CONFIG_SND_OSSEMUL=y
CONFIG_SND_MIXER_OSS=y
CONFIG_SND_PCM_OSS=y
CONFIG_SND_SEQUENCER_OSS=y
CONFIG_SND_AC97_CODEC=y
CONFIG_SND_AC97_BUS=y
CONFIG_SND_INTEL8X0=y
CONFIG_USB_ARCH_HAS_HCD=y
CONFIG_USB_ARCH_HAS_OHCI=y
CONFIG_USB=y
CONFIG_USB_DEVICEFS=y
CONFIG_USB_EHCI_HCD=y
CONFIG_USB_OHCI_HCD=y
CONFIG_USB_OHCI_LITTLE_ENDIAN=y
CONFIG_USB_PRINTER=y
CONFIG_USB_STORAGE=y
CONFIG_USB_HID=y
CONFIG_USB_HIDINPUT=y
CONFIG_USB_EGALAX=m
CONFIG_USB_MON=y
CONFIG_EXT2_FS=y
CONFIG_EXT3_FS=y
CONFIG_EXT3_FS_XATTR=y
CONFIG_JBD=y
CONFIG_FS_MBCACHE=y
CONFIG_REISERFS_FS=y
CONFIG_INOTIFY=y
CONFIG_DNOTIFY=y
CONFIG_AUTOFS4_FS=y
CONFIG_ISO9660_FS=y
CONFIG_JOLIET=y
CONFIG_UDF_FS=y
CONFIG_UDF_NLS=y
CONFIG_FAT_FS=y
CONFIG_MSDOS_FS=y
CONFIG_VFAT_FS=y
CONFIG_FAT_DEFAULT_CODEPAGE=437
CONFIG_FAT_DEFAULT_IOCHARSET="iso8859-1"
CONFIG_PROC_FS=y
CONFIG_PROC_KCORE=y
CONFIG_SYSFS=y
CONFIG_TMPFS=y
CONFIG_RAMFS=y
CONFIG_NFS_FS=y
CONFIG_NFSD=y
CONFIG_NFSD_TCP=y
CONFIG_LOCKD=y
CONFIG_EXPORTFS=y
CONFIG_NFS_COMMON=y
CONFIG_SUNRPC=y
CONFIG_SMB_FS=y
CONFIG_MSDOS_PARTITION=y
CONFIG_NLS=y
CONFIG_NLS_DEFAULT="iso8859-1"
CONFIG_NLS_CODEPAGE_437=y
CONFIG_NLS_ISO8859_1=y
CONFIG_PROFILING=y
CONFIG_OPROFILE=y
CONFIG_LOG_BUF_SHIFT=15
CONFIG_DEBUG_BUGVERBOSE=y
CONFIG_EARLY_PRINTK=y
CONFIG_X86_FIND_SMP_CONFIG=y
CONFIG_X86_MPPARSE=y
CONFIG_CRYPTO=y
CONFIG_CRC32=y
CONFIG_LIBCRC32C=m
CONFIG_GENERIC_HARDIRQS=y
CONFIG_GENERIC_IRQ_PROBE=y
CONFIG_GENERIC_PENDING_IRQ=y
CONFIG_X86_SMP=y
CONFIG_X86_HT=y
CONFIG_X86_BIOS_REBOOT=y
CONFIG_X86_TRAMPOLINE=y
CONFIG_PC=y