linux/Documentation/ide/ide.txt
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   1
   2        Information regarding the Enhanced IDE drive in Linux 2.6
   3
   4==============================================================================
   5
   6
   7   The hdparm utility can be used to control various IDE features on a
   8   running system. It is packaged separately.  Please Look for it on popular
   9   linux FTP sites.
  10
  11
  12
  13***  IMPORTANT NOTICES:  BUGGY IDE CHIPSETS CAN CORRUPT DATA!!
  14***  =================
  15***  PCI versions of the CMD640 and RZ1000 interfaces are now detected
  16***  automatically at startup when PCI BIOS support is configured.
  17***
  18***  Linux disables the "prefetch" ("readahead") mode of the RZ1000
  19***  to prevent data corruption possible due to hardware design flaws.
  20***
  21***  For the CMD640, linux disables "IRQ unmasking" (hdparm -u1) on any
  22***  drive for which the "prefetch" mode of the CMD640 is turned on.
  23***  If "prefetch" is disabled (hdparm -p8), then "IRQ unmasking" can be
  24***  used again.
  25***
  26***  For the CMD640, linux disables "32bit I/O" (hdparm -c1) on any drive
  27***  for which the "prefetch" mode of the CMD640 is turned off.
  28***  If "prefetch" is enabled (hdparm -p9), then "32bit I/O" can be
  29***  used again.
  30***
  31***  The CMD640 is also used on some Vesa Local Bus (VLB) cards, and is *NOT*
  32***  automatically detected by Linux.  For safe, reliable operation with such
  33***  interfaces, one *MUST* use the "cmd640.probe_vlb" kernel option.
  34***
  35***  Use of the "serialize" option is no longer necessary.
  36
  37================================================================================
  38Common pitfalls:
  39
  40- 40-conductor IDE cables are capable of transferring data in DMA modes up to
  41  udma2, but no faster.
  42
  43- If possible devices should be attached to separate channels if they are
  44  available. Typically the disk on the first and CD-ROM on the second.
  45
  46- If you mix devices on the same cable, please consider using similar devices
  47  in respect of the data transfer mode they support.
  48
  49- Even better try to stick to the same vendor and device type on the same
  50  cable.
  51
  52================================================================================
  53
  54This is the multiple IDE interface driver, as evolved from hd.c.
  55
  56It supports up to 9 IDE interfaces per default, on one or more IRQs (usually
  5714 & 15).  There can be up to two drives per interface, as per the ATA-6 spec.
  58
  59Primary:    ide0, port 0x1f0; major=3;  hda is minor=0; hdb is minor=64
  60Secondary:  ide1, port 0x170; major=22; hdc is minor=0; hdd is minor=64
  61Tertiary:   ide2, port 0x1e8; major=33; hde is minor=0; hdf is minor=64
  62Quaternary: ide3, port 0x168; major=34; hdg is minor=0; hdh is minor=64
  63fifth..     ide4, usually PCI, probed
  64sixth..     ide5, usually PCI, probed
  65
  66To access devices on interfaces > ide0, device entries please make sure that
  67device files for them are present in /dev.  If not, please create such
  68entries, by using /dev/MAKEDEV.
  69
  70This driver automatically probes for most IDE interfaces (including all PCI
  71ones), for the drives/geometries attached to those interfaces, and for the IRQ
  72lines being used by the interfaces (normally 14, 15 for ide0/ide1).
  73
  74Any number of interfaces may share a single IRQ if necessary, at a slight
  75performance penalty, whether on separate cards or a single VLB card.
  76The IDE driver automatically detects and handles this.  However, this may
  77or may not be harmful to your hardware.. two or more cards driving the same IRQ
  78can potentially burn each other's bus driver, though in practice this
  79seldom occurs.  Be careful, and if in doubt, don't do it!
  80
  81Drives are normally found by auto-probing and/or examining the CMOS/BIOS data.
  82For really weird situations, the apparent (fdisk) geometry can also be specified
  83on the kernel "command line" using LILO.  The format of such lines is:
  84
  85        ide_core.chs=[interface_number.device_number]:cyls,heads,sects
  86or      ide_core.cdrom=[interface_number.device_number]
  87
  88For example:
  89
  90        ide_core.chs=1.0:1050,32,64  ide_core.cdrom=1.1
  91
  92The results of successful auto-probing may override the physical geometry/irq
  93specified, though the "original" geometry may be retained as the "logical"
  94geometry for partitioning purposes (fdisk).
  95
  96If the auto-probing during boot time confuses a drive (ie. the drive works
  97with hd.c but not with ide.c), then an command line option may be specified
  98for each drive for which you'd like the drive to skip the hardware
  99probe/identification sequence.  For example:
 100
 101        ide_core.noprobe=0.1
 102or
 103        ide_core.chs=1.0:768,16,32
 104        ide_core.noprobe=1.0
 105
 106Note that when only one IDE device is attached to an interface, it should be
 107jumpered as "single" or "master", *not* "slave".  Many folks have had
 108"trouble" with cdroms because of this requirement, so the driver now probes
 109for both units, though success is more likely when the drive is jumpered
 110correctly.
 111
 112Courtesy of Scott Snyder and others, the driver supports ATAPI cdrom drives
 113such as the NEC-260 and the new MITSUMI triple/quad speed drives.
 114Such drives will be identified at boot time, just like a hard disk.
 115
 116If for some reason your cdrom drive is *not* found at boot time, you can force
 117the probe to look harder by supplying a kernel command line parameter
 118via LILO, such as:
 119
 120        ide_core.cdrom=1.0      /* "master" on second interface (hdc) */
 121or
 122        ide_core.cdrom=1.1      /* "slave" on second interface (hdd) */
 123
 124For example, a GW2000 system might have a hard drive on the primary
 125interface (/dev/hda) and an IDE cdrom drive on the secondary interface
 126(/dev/hdc).  To mount a CD in the cdrom drive, one would use something like:
 127
 128        ln -sf /dev/hdc /dev/cdrom
 129        mkdir /mnt/cdrom
 130        mount /dev/cdrom /mnt/cdrom -t iso9660 -o ro
 131
 132If, after doing all of the above, mount doesn't work and you see
 133errors from the driver (with dmesg) complaining about `status=0xff',
 134this means that the hardware is not responding to the driver's attempts
 135to read it.  One of the following is probably the problem:
 136
 137  - Your hardware is broken.
 138
 139  - You are using the wrong address for the device, or you have the
 140    drive jumpered wrong.  Review the configuration instructions above.
 141
 142  - Your IDE controller requires some nonstandard initialization sequence
 143    before it will work properly.  If this is the case, there will often
 144    be a separate MS-DOS driver just for the controller.  IDE interfaces
 145    on sound cards usually fall into this category.  Such configurations
 146    can often be made to work by first booting MS-DOS, loading the
 147    appropriate drivers, and then warm-booting linux (without powering
 148    off).  This can be automated using loadlin in the MS-DOS autoexec.
 149
 150If you always get timeout errors, interrupts from the drive are probably
 151not making it to the host.  Check how you have the hardware jumpered
 152and make sure it matches what the driver expects (see the configuration
 153instructions above).  If you have a PCI system, also check the BIOS
 154setup; I've had one report of a system which was shipped with IRQ 15
 155disabled by the BIOS.
 156
 157The kernel is able to execute binaries directly off of the cdrom,
 158provided it is mounted with the default block size of 1024 (as above).
 159
 160Please pass on any feedback on any of this stuff to the maintainer,
 161whose address can be found in linux/MAINTAINERS.
 162
 163The IDE driver is modularized.  The high level disk/CD-ROM/tape/floppy
 164drivers can always be compiled as loadable modules, the chipset drivers
 165can only be compiled into the kernel, and the core code (ide.c) can be
 166compiled as a loadable module provided no chipset support is needed.
 167
 168When using ide.c as a module in combination with kmod, add:
 169
 170        alias block-major-3 ide-probe
 171
 172to a configuration file in /etc/modprobe.d/.
 173
 174When ide.c is used as a module, you can pass command line parameters to the
 175driver using the "options=" keyword to insmod, while replacing any ',' with
 176';'.
 177
 178
 179================================================================================
 180
 181Summary of ide driver parameters for kernel command line
 182--------------------------------------------------------
 183
 184For legacy IDE VLB host drivers (ali14xx/dtc2278/ht6560b/qd65xx/umc8672)
 185you need to explicitly enable probing by using "probe" kernel parameter,
 186i.e. to enable probing for ALI M14xx chipsets (ali14xx host driver) use:
 187
 188* "ali14xx.probe" boot option when ali14xx driver is built-in the kernel
 189
 190* "probe" module parameter when ali14xx driver is compiled as module
 191  ("modprobe ali14xx probe")
 192
 193Also for legacy CMD640 host driver (cmd640) you need to use "probe_vlb"
 194kernel paremeter to enable probing for VLB version of the chipset (PCI ones
 195are detected automatically).
 196
 197You also need to use "probe" kernel parameter for ide-4drives driver
 198(support for IDE generic chipset with four drives on one port).
 199
 200To enable support for IDE doublers on Amiga use "doubler" kernel parameter
 201for gayle host driver (i.e. "gayle.doubler" if the driver is built-in).
 202
 203To force ignoring cable detection (this should be needed only if you're using
 204short 40-wires cable which cannot be automatically detected - if this is not
 205a case please report it as a bug instead) use "ignore_cable" kernel parameter:
 206
 207* "ide_core.ignore_cable=[interface_number]" boot option if IDE is built-in
 208  (i.e. "ide_core.ignore_cable=1" to force ignoring cable for "ide1")
 209
 210* "ignore_cable=[interface_number]" module parameter (for ide_core module)
 211  if IDE is compiled as module
 212
 213Other kernel parameters for ide_core are:
 214
 215* "nodma=[interface_number.device_number]" to disallow DMA for a device
 216
 217* "noflush=[interface_number.device_number]" to disable flush requests
 218
 219* "nohpa=[interface_number.device_number]" to disable Host Protected Area
 220
 221* "noprobe=[interface_number.device_number]" to skip probing
 222
 223* "nowerr=[interface_number.device_number]" to ignore the WRERR_STAT bit
 224
 225* "cdrom=[interface_number.device_number]" to force device as a CD-ROM
 226
 227* "chs=[interface_number.device_number]" to force device as a disk (using CHS)
 228
 229================================================================================
 230
 231Some Terminology
 232----------------
 233IDE = Integrated Drive Electronics, meaning that each drive has a built-in
 234controller, which is why an "IDE interface card" is not a "controller card".
 235
 236ATA = AT (the old IBM 286 computer) Attachment Interface, a draft American
 237National Standard for connecting hard drives to PCs.  This is the official
 238name for "IDE".
 239
 240The latest standards define some enhancements, known as the ATA-6 spec,
 241which grew out of vendor-specific "Enhanced IDE" (EIDE) implementations.
 242
 243ATAPI = ATA Packet Interface, a new protocol for controlling the drives,
 244similar to SCSI protocols, created at the same time as the ATA2 standard.
 245ATAPI is currently used for controlling CDROM, TAPE and FLOPPY (ZIP or
 246LS120/240) devices, removable R/W cartridges, and for high capacity hard disk
 247drives.
 248
 249mlord@pobox.com
 250--
 251
 252Wed Apr 17 22:52:44 CEST 2002 edited by Marcin Dalecki, the current
 253maintainer.
 254
 255Wed Aug 20 22:31:29 CEST 2003 updated ide boot options to current ide.c
 256comments at 2.6.0-test4 time. Maciej Soltysiak <solt@dns.toxicfilms.tv>
 257
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