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diff --git a/Documentation/ide/ide.rst b/Documentation/ide/ide.rst new file mode 100644 index 000000000000..88bdcba92f7d --- /dev/null +++ b/Documentation/ide/ide.rst @@ -0,0 +1,265 @@ +============================================ +Information regarding the Enhanced IDE drive +============================================ + + The hdparm utility can be used to control various IDE features on a + running system. It is packaged separately. Please Look for it on popular + linux FTP sites. + +------------------------------------------------------------------------------- + +.. important:: + + BUGGY IDE CHIPSETS CAN CORRUPT DATA!! + + PCI versions of the CMD640 and RZ1000 interfaces are now detected + automatically at startup when PCI BIOS support is configured. + + Linux disables the "prefetch" ("readahead") mode of the RZ1000 + to prevent data corruption possible due to hardware design flaws. + + For the CMD640, linux disables "IRQ unmasking" (hdparm -u1) on any + drive for which the "prefetch" mode of the CMD640 is turned on. + If "prefetch" is disabled (hdparm -p8), then "IRQ unmasking" can be + used again. + + For the CMD640, linux disables "32bit I/O" (hdparm -c1) on any drive + for which the "prefetch" mode of the CMD640 is turned off. + If "prefetch" is enabled (hdparm -p9), then "32bit I/O" can be + used again. + + The CMD640 is also used on some Vesa Local Bus (VLB) cards, and is *NOT* + automatically detected by Linux. For safe, reliable operation with such + interfaces, one *MUST* use the "cmd640.probe_vlb" kernel option. + + Use of the "serialize" option is no longer necessary. + +------------------------------------------------------------------------------- + +Common pitfalls +=============== + +- 40-conductor IDE cables are capable of transferring data in DMA modes up to + udma2, but no faster. + +- If possible devices should be attached to separate channels if they are + available. Typically the disk on the first and CD-ROM on the second. + +- If you mix devices on the same cable, please consider using similar devices + in respect of the data transfer mode they support. + +- Even better try to stick to the same vendor and device type on the same + cable. + +This is the multiple IDE interface driver, as evolved from hd.c +=============================================================== + +It supports up to 9 IDE interfaces per default, on one or more IRQs (usually +14 & 15). There can be up to two drives per interface, as per the ATA-6 spec.:: + + Primary: ide0, port 0x1f0; major=3; hda is minor=0; hdb is minor=64 + Secondary: ide1, port 0x170; major=22; hdc is minor=0; hdd is minor=64 + Tertiary: ide2, port 0x1e8; major=33; hde is minor=0; hdf is minor=64 + Quaternary: ide3, port 0x168; major=34; hdg is minor=0; hdh is minor=64 + fifth.. ide4, usually PCI, probed + sixth.. ide5, usually PCI, probed + +To access devices on interfaces > ide0, device entries please make sure that +device files for them are present in /dev. If not, please create such +entries, by using /dev/MAKEDEV. + +This driver automatically probes for most IDE interfaces (including all PCI +ones), for the drives/geometries attached to those interfaces, and for the IRQ +lines being used by the interfaces (normally 14, 15 for ide0/ide1). + +Any number of interfaces may share a single IRQ if necessary, at a slight +performance penalty, whether on separate cards or a single VLB card. +The IDE driver automatically detects and handles this. However, this may +or may not be harmful to your hardware.. two or more cards driving the same IRQ +can potentially burn each other's bus driver, though in practice this +seldom occurs. Be careful, and if in doubt, don't do it! + +Drives are normally found by auto-probing and/or examining the CMOS/BIOS data. +For really weird situations, the apparent (fdisk) geometry can also be specified +on the kernel "command line" using LILO. The format of such lines is:: + + ide_core.chs=[interface_number.device_number]:cyls,heads,sects + +or:: + + ide_core.cdrom=[interface_number.device_number] + +For example:: + + ide_core.chs=1.0:1050,32,64 ide_core.cdrom=1.1 + +The results of successful auto-probing may override the physical geometry/irq +specified, though the "original" geometry may be retained as the "logical" +geometry for partitioning purposes (fdisk). + +If the auto-probing during boot time confuses a drive (ie. the drive works +with hd.c but not with ide.c), then an command line option may be specified +for each drive for which you'd like the drive to skip the hardware +probe/identification sequence. For example:: + + ide_core.noprobe=0.1 + +or:: + + ide_core.chs=1.0:768,16,32 + ide_core.noprobe=1.0 + +Note that when only one IDE device is attached to an interface, it should be +jumpered as "single" or "master", *not* "slave". Many folks have had +"trouble" with cdroms because of this requirement, so the driver now probes +for both units, though success is more likely when the drive is jumpered +correctly. + +Courtesy of Scott Snyder and others, the driver supports ATAPI cdrom drives +such as the NEC-260 and the new MITSUMI triple/quad speed drives. +Such drives will be identified at boot time, just like a hard disk. + +If for some reason your cdrom drive is *not* found at boot time, you can force +the probe to look harder by supplying a kernel command line parameter +via LILO, such as::: + + ide_core.cdrom=1.0 /* "master" on second interface (hdc) */ + +or:: + + ide_core.cdrom=1.1 /* "slave" on second interface (hdd) */ + +For example, a GW2000 system might have a hard drive on the primary +interface (/dev/hda) and an IDE cdrom drive on the secondary interface +(/dev/hdc). To mount a CD in the cdrom drive, one would use something like:: + + ln -sf /dev/hdc /dev/cdrom + mkdir /mnt/cdrom + mount /dev/cdrom /mnt/cdrom -t iso9660 -o ro + +If, after doing all of the above, mount doesn't work and you see +errors from the driver (with dmesg) complaining about `status=0xff`, +this means that the hardware is not responding to the driver's attempts +to read it. One of the following is probably the problem: + + - Your hardware is broken. + + - You are using the wrong address for the device, or you have the + drive jumpered wrong. Review the configuration instructions above. + + - Your IDE controller requires some nonstandard initialization sequence + before it will work properly. If this is the case, there will often + be a separate MS-DOS driver just for the controller. IDE interfaces + on sound cards usually fall into this category. Such configurations + can often be made to work by first booting MS-DOS, loading the + appropriate drivers, and then warm-booting linux (without powering + off). This can be automated using loadlin in the MS-DOS autoexec. + +If you always get timeout errors, interrupts from the drive are probably +not making it to the host. Check how you have the hardware jumpered +and make sure it matches what the driver expects (see the configuration +instructions above). If you have a PCI system, also check the BIOS +setup; I've had one report of a system which was shipped with IRQ 15 +disabled by the BIOS. + +The kernel is able to execute binaries directly off of the cdrom, +provided it is mounted with the default block size of 1024 (as above). + +Please pass on any feedback on any of this stuff to the maintainer, +whose address can be found in linux/MAINTAINERS. + +The IDE driver is modularized. The high level disk/CD-ROM/tape/floppy +drivers can always be compiled as loadable modules, the chipset drivers +can only be compiled into the kernel, and the core code (ide.c) can be +compiled as a loadable module provided no chipset support is needed. + +When using ide.c as a module in combination with kmod, add:: + + alias block-major-3 ide-probe + +to a configuration file in /etc/modprobe.d/. + +When ide.c is used as a module, you can pass command line parameters to the +driver using the "options=" keyword to insmod, while replacing any ',' with +';'. + + +Summary of ide driver parameters for kernel command line +======================================================== + +For legacy IDE VLB host drivers (ali14xx/dtc2278/ht6560b/qd65xx/umc8672) +you need to explicitly enable probing by using "probe" kernel parameter, +i.e. to enable probing for ALI M14xx chipsets (ali14xx host driver) use: + +* "ali14xx.probe" boot option when ali14xx driver is built-in the kernel + +* "probe" module parameter when ali14xx driver is compiled as module + ("modprobe ali14xx probe") + +Also for legacy CMD640 host driver (cmd640) you need to use "probe_vlb" +kernel paremeter to enable probing for VLB version of the chipset (PCI ones +are detected automatically). + +You also need to use "probe" kernel parameter for ide-4drives driver +(support for IDE generic chipset with four drives on one port). + +To enable support for IDE doublers on Amiga use "doubler" kernel parameter +for gayle host driver (i.e. "gayle.doubler" if the driver is built-in). + +To force ignoring cable detection (this should be needed only if you're using +short 40-wires cable which cannot be automatically detected - if this is not +a case please report it as a bug instead) use "ignore_cable" kernel parameter: + +* "ide_core.ignore_cable=[interface_number]" boot option if IDE is built-in + (i.e. "ide_core.ignore_cable=1" to force ignoring cable for "ide1") + +* "ignore_cable=[interface_number]" module parameter (for ide_core module) + if IDE is compiled as module + +Other kernel parameters for ide_core are: + +* "nodma=[interface_number.device_number]" to disallow DMA for a device + +* "noflush=[interface_number.device_number]" to disable flush requests + +* "nohpa=[interface_number.device_number]" to disable Host Protected Area + +* "noprobe=[interface_number.device_number]" to skip probing + +* "nowerr=[interface_number.device_number]" to ignore the WRERR_STAT bit + +* "cdrom=[interface_number.device_number]" to force device as a CD-ROM + +* "chs=[interface_number.device_number]" to force device as a disk (using CHS) + + +Some Terminology +================ + +IDE + Integrated Drive Electronics, meaning that each drive has a built-in + controller, which is why an "IDE interface card" is not a "controller card". + +ATA + AT (the old IBM 286 computer) Attachment Interface, a draft American + National Standard for connecting hard drives to PCs. This is the official + name for "IDE". + + The latest standards define some enhancements, known as the ATA-6 spec, + which grew out of vendor-specific "Enhanced IDE" (EIDE) implementations. + +ATAPI + ATA Packet Interface, a new protocol for controlling the drives, + similar to SCSI protocols, created at the same time as the ATA2 standard. + ATAPI is currently used for controlling CDROM, TAPE and FLOPPY (ZIP or + LS120/240) devices, removable R/W cartridges, and for high capacity hard disk + drives. + +mlord@pobox.com + + +Wed Apr 17 22:52:44 CEST 2002 edited by Marcin Dalecki, the current +maintainer. + +Wed Aug 20 22:31:29 CEST 2003 updated ide boot options to current ide.c +comments at 2.6.0-test4 time. Maciej Soltysiak <solt@dns.toxicfilms.tv> |