266 lines
11 KiB
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266 lines
11 KiB
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============================================
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Information regarding the Enhanced IDE drive
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============================================
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The hdparm utility can be used to control various IDE features on a
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running system. It is packaged separately. Please Look for it on popular
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linux FTP sites.
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-------------------------------------------------------------------------------
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.. important::
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BUGGY IDE CHIPSETS CAN CORRUPT DATA!!
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PCI versions of the CMD640 and RZ1000 interfaces are now detected
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automatically at startup when PCI BIOS support is configured.
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Linux disables the "prefetch" ("readahead") mode of the RZ1000
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to prevent data corruption possible due to hardware design flaws.
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For the CMD640, linux disables "IRQ unmasking" (hdparm -u1) on any
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drive for which the "prefetch" mode of the CMD640 is turned on.
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If "prefetch" is disabled (hdparm -p8), then "IRQ unmasking" can be
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used again.
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For the CMD640, linux disables "32bit I/O" (hdparm -c1) on any drive
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for which the "prefetch" mode of the CMD640 is turned off.
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If "prefetch" is enabled (hdparm -p9), then "32bit I/O" can be
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used again.
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The CMD640 is also used on some Vesa Local Bus (VLB) cards, and is *NOT*
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automatically detected by Linux. For safe, reliable operation with such
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interfaces, one *MUST* use the "cmd640.probe_vlb" kernel option.
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Use of the "serialize" option is no longer necessary.
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-------------------------------------------------------------------------------
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Common pitfalls
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===============
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- 40-conductor IDE cables are capable of transferring data in DMA modes up to
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udma2, but no faster.
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- If possible devices should be attached to separate channels if they are
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available. Typically the disk on the first and CD-ROM on the second.
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- If you mix devices on the same cable, please consider using similar devices
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in respect of the data transfer mode they support.
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- Even better try to stick to the same vendor and device type on the same
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cable.
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This is the multiple IDE interface driver, as evolved from hd.c
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===============================================================
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It supports up to 9 IDE interfaces per default, on one or more IRQs (usually
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14 & 15). There can be up to two drives per interface, as per the ATA-6 spec.::
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Primary: ide0, port 0x1f0; major=3; hda is minor=0; hdb is minor=64
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Secondary: ide1, port 0x170; major=22; hdc is minor=0; hdd is minor=64
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Tertiary: ide2, port 0x1e8; major=33; hde is minor=0; hdf is minor=64
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Quaternary: ide3, port 0x168; major=34; hdg is minor=0; hdh is minor=64
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fifth.. ide4, usually PCI, probed
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sixth.. ide5, usually PCI, probed
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To access devices on interfaces > ide0, device entries please make sure that
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device files for them are present in /dev. If not, please create such
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entries, by using /dev/MAKEDEV.
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This driver automatically probes for most IDE interfaces (including all PCI
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ones), for the drives/geometries attached to those interfaces, and for the IRQ
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lines being used by the interfaces (normally 14, 15 for ide0/ide1).
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Any number of interfaces may share a single IRQ if necessary, at a slight
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performance penalty, whether on separate cards or a single VLB card.
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The IDE driver automatically detects and handles this. However, this may
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or may not be harmful to your hardware.. two or more cards driving the same IRQ
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can potentially burn each other's bus driver, though in practice this
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seldom occurs. Be careful, and if in doubt, don't do it!
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Drives are normally found by auto-probing and/or examining the CMOS/BIOS data.
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For really weird situations, the apparent (fdisk) geometry can also be specified
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on the kernel "command line" using LILO. The format of such lines is::
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ide_core.chs=[interface_number.device_number]:cyls,heads,sects
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or::
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ide_core.cdrom=[interface_number.device_number]
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For example::
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ide_core.chs=1.0:1050,32,64 ide_core.cdrom=1.1
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The results of successful auto-probing may override the physical geometry/irq
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specified, though the "original" geometry may be retained as the "logical"
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geometry for partitioning purposes (fdisk).
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If the auto-probing during boot time confuses a drive (ie. the drive works
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with hd.c but not with ide.c), then an command line option may be specified
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for each drive for which you'd like the drive to skip the hardware
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probe/identification sequence. For example::
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ide_core.noprobe=0.1
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or::
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ide_core.chs=1.0:768,16,32
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ide_core.noprobe=1.0
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Note that when only one IDE device is attached to an interface, it should be
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jumpered as "single" or "master", *not* "slave". Many folks have had
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"trouble" with cdroms because of this requirement, so the driver now probes
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for both units, though success is more likely when the drive is jumpered
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correctly.
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Courtesy of Scott Snyder and others, the driver supports ATAPI cdrom drives
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such as the NEC-260 and the new MITSUMI triple/quad speed drives.
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Such drives will be identified at boot time, just like a hard disk.
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If for some reason your cdrom drive is *not* found at boot time, you can force
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the probe to look harder by supplying a kernel command line parameter
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via LILO, such as:::
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ide_core.cdrom=1.0 /* "master" on second interface (hdc) */
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or::
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ide_core.cdrom=1.1 /* "slave" on second interface (hdd) */
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For example, a GW2000 system might have a hard drive on the primary
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interface (/dev/hda) and an IDE cdrom drive on the secondary interface
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(/dev/hdc). To mount a CD in the cdrom drive, one would use something like::
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ln -sf /dev/hdc /dev/cdrom
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mkdir /mnt/cdrom
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mount /dev/cdrom /mnt/cdrom -t iso9660 -o ro
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If, after doing all of the above, mount doesn't work and you see
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errors from the driver (with dmesg) complaining about `status=0xff`,
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this means that the hardware is not responding to the driver's attempts
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to read it. One of the following is probably the problem:
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- Your hardware is broken.
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- You are using the wrong address for the device, or you have the
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drive jumpered wrong. Review the configuration instructions above.
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- Your IDE controller requires some nonstandard initialization sequence
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before it will work properly. If this is the case, there will often
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be a separate MS-DOS driver just for the controller. IDE interfaces
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on sound cards usually fall into this category. Such configurations
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can often be made to work by first booting MS-DOS, loading the
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appropriate drivers, and then warm-booting linux (without powering
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off). This can be automated using loadlin in the MS-DOS autoexec.
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If you always get timeout errors, interrupts from the drive are probably
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not making it to the host. Check how you have the hardware jumpered
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and make sure it matches what the driver expects (see the configuration
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instructions above). If you have a PCI system, also check the BIOS
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setup; I've had one report of a system which was shipped with IRQ 15
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disabled by the BIOS.
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The kernel is able to execute binaries directly off of the cdrom,
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provided it is mounted with the default block size of 1024 (as above).
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Please pass on any feedback on any of this stuff to the maintainer,
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whose address can be found in linux/MAINTAINERS.
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The IDE driver is modularized. The high level disk/CD-ROM/tape/floppy
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drivers can always be compiled as loadable modules, the chipset drivers
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can only be compiled into the kernel, and the core code (ide.c) can be
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compiled as a loadable module provided no chipset support is needed.
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When using ide.c as a module in combination with kmod, add::
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alias block-major-3 ide-probe
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to a configuration file in /etc/modprobe.d/.
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When ide.c is used as a module, you can pass command line parameters to the
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driver using the "options=" keyword to insmod, while replacing any ',' with
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';'.
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Summary of ide driver parameters for kernel command line
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========================================================
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For legacy IDE VLB host drivers (ali14xx/dtc2278/ht6560b/qd65xx/umc8672)
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you need to explicitly enable probing by using "probe" kernel parameter,
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i.e. to enable probing for ALI M14xx chipsets (ali14xx host driver) use:
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* "ali14xx.probe" boot option when ali14xx driver is built-in the kernel
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* "probe" module parameter when ali14xx driver is compiled as module
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("modprobe ali14xx probe")
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Also for legacy CMD640 host driver (cmd640) you need to use "probe_vlb"
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kernel paremeter to enable probing for VLB version of the chipset (PCI ones
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are detected automatically).
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You also need to use "probe" kernel parameter for ide-4drives driver
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(support for IDE generic chipset with four drives on one port).
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To enable support for IDE doublers on Amiga use "doubler" kernel parameter
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for gayle host driver (i.e. "gayle.doubler" if the driver is built-in).
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To force ignoring cable detection (this should be needed only if you're using
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short 40-wires cable which cannot be automatically detected - if this is not
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a case please report it as a bug instead) use "ignore_cable" kernel parameter:
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* "ide_core.ignore_cable=[interface_number]" boot option if IDE is built-in
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(i.e. "ide_core.ignore_cable=1" to force ignoring cable for "ide1")
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* "ignore_cable=[interface_number]" module parameter (for ide_core module)
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if IDE is compiled as module
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Other kernel parameters for ide_core are:
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* "nodma=[interface_number.device_number]" to disallow DMA for a device
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* "noflush=[interface_number.device_number]" to disable flush requests
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* "nohpa=[interface_number.device_number]" to disable Host Protected Area
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* "noprobe=[interface_number.device_number]" to skip probing
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* "nowerr=[interface_number.device_number]" to ignore the WRERR_STAT bit
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* "cdrom=[interface_number.device_number]" to force device as a CD-ROM
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* "chs=[interface_number.device_number]" to force device as a disk (using CHS)
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Some Terminology
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================
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IDE
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Integrated Drive Electronics, meaning that each drive has a built-in
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controller, which is why an "IDE interface card" is not a "controller card".
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ATA
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AT (the old IBM 286 computer) Attachment Interface, a draft American
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National Standard for connecting hard drives to PCs. This is the official
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name for "IDE".
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The latest standards define some enhancements, known as the ATA-6 spec,
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which grew out of vendor-specific "Enhanced IDE" (EIDE) implementations.
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ATAPI
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ATA Packet Interface, a new protocol for controlling the drives,
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similar to SCSI protocols, created at the same time as the ATA2 standard.
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ATAPI is currently used for controlling CDROM, TAPE and FLOPPY (ZIP or
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LS120/240) devices, removable R/W cartridges, and for high capacity hard disk
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drives.
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mlord@pobox.com
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Wed Apr 17 22:52:44 CEST 2002 edited by Marcin Dalecki, the current
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maintainer.
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Wed Aug 20 22:31:29 CEST 2003 updated ide boot options to current ide.c
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comments at 2.6.0-test4 time. Maciej Soltysiak <solt@dns.toxicfilms.tv>
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