| Information regarding the Enhanced IDE drive in Linux 2.6 | |
| ============================================================================== | |
| 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 NOTICES: 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> |