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 "ide0=cmd640_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). For special cases, interfaces may be specified using kernel "command line" options. For example, ide3=0x168,0x36e,10 /* ioports 0x168-0x16f,0x36e, irq 10 */ Normally the irq number need not be specified, as ide.c will probe for it: ide3=0x168,0x36e /* ioports 0x168-0x16f,0x36e */ The standard port, and irq values are these: ide0=0x1f0,0x3f6,14 ide1=0x170,0x376,15 ide2=0x1e8,0x3ee,11 ide3=0x168,0x36e,10 Note that the first parameter reserves 8 contiguous ioports, whereas the second value denotes a single ioport. If in doubt, do a 'cat /proc/ioports'. In all probability the device uses these ports and IRQs if it is attached to the appropriate ide channel. Pass the parameter for the correct ide channel to the kernel, as explained above. 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: hdx=cyls,heads,sects,wpcom,irq or hdx=cdrom where hdx can be any of hda through hdh, Three values are required (cyls,heads,sects). For example: hdc=1050,32,64 hdd=cdrom either {hda,hdb} or {hdc,hdd}. 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: hdb=noprobe or hdc=768,16,32 hdc=noprobe 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: hdc=cdrom /* hdc = "master" on second interface */ or hdd=cdrom /* hdd = "slave" on second interface */ 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. Note that if BOTH hd.c and ide.c are configured into the kernel, hd.c will normally be allowed to control the primary IDE interface. This is useful for older hardware that may be incompatible with ide.c, and still allows newer hardware to run on the 2nd/3rd/4th IDE ports under control of ide.c. To have ide.c also "take over" the primary IDE port in this situation, use the "command line" parameter: ide0=0x1f0 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 /etc/modprobe.conf. 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 ';'. For example: insmod ide.o options="ide0=serialize ide1=serialize ide2=0x1e8;0x3ee;11" ================================================================================ Summary of ide driver parameters for kernel command line -------------------------------------------------------- "hdx=" is recognized for all "x" from "a" to "h", such as "hdc". "idex=" is recognized for all "x" from "0" to "3", such as "ide1". "hdx=noprobe" : drive may be present, but do not probe for it "hdx=none" : drive is NOT present, ignore cmos and do not probe "hdx=nowerr" : ignore the WRERR_STAT bit on this drive "hdx=cdrom" : drive is present, and is a cdrom drive "hdx=cyl,head,sect" : disk drive is present, with specified geometry "hdx=remap" : remap access of sector 0 to sector 1 (for EZDrive) "hdx=remap63" : remap the drive: add 63 to all sector numbers (for DM OnTrack) "hdx=autotune" : driver will attempt to tune interface speed to the fastest PIO mode supported, if possible for this drive only. Not fully supported by all chipset types, and quite likely to cause trouble with older/odd IDE drives. "hdx=swapdata" : when the drive is a disk, byte swap all data "hdx=bswap" : same as above.......... "hdx=scsi" : the return of the ide-scsi flag, this is useful for allowing ide-floppy, ide-tape, and ide-cdrom|writers to use ide-scsi emulation on a device specific option. "idebus=xx" : inform IDE driver of VESA/PCI bus speed in MHz, where "xx" is between 20 and 66 inclusive, used when tuning chipset PIO modes. For PCI bus, 25 is correct for a P75 system, 30 is correct for P90,P120,P180 systems, and 33 is used for P100,P133,P166 systems. If in doubt, use idebus=33 for PCI. As for VLB, it is safest to not specify it. Bigger values are safer than smaller ones. "idex=noprobe" : do not attempt to access/use this interface "idex=base" : probe for an interface at the addr specified, where "base" is usually 0x1f0 or 0x170 and "ctl" is assumed to be "base"+0x206 "idex=base,ctl" : specify both base and ctl "idex=base,ctl,irq" : specify base, ctl, and irq number "idex=autotune" : driver will attempt to tune interface speed to the fastest PIO mode supported, for all drives on this interface. Not fully supported by all chipset types, and quite likely to cause trouble with older/odd IDE drives. "idex=noautotune" : driver will NOT attempt to tune interface speed This is the default for most chipsets, except the cmd640. "idex=serialize" : do not overlap operations on idex. Please note that you will have to specify this option for both the respecitve primary and secondary channel to take effect. "idex=four" : four drives on idex and ide(x^1) share same ports "idex=reset" : reset interface after probe "idex=dma" : automatically configure/use DMA if possible. "idex=ata66" : informs the interface that it has an 80c cable for chipsets that are ATA-66 capable, but the ability to bit test for detection is currently unknown. "ide=reverse" : formerly called to pci sub-system, but now local. "ide=nodma" : disable DMA globally for the IDE subsystem. The following are valid ONLY on ide0, which usually corresponds to the first ATA interface found on the particular host, and the defaults for the base,ctl ports must not be altered. "ide0=dtc2278" : probe/support DTC2278 interface "ide0=ht6560b" : probe/support HT6560B interface "ide0=cmd640_vlb" : *REQUIRED* for VLB cards with the CMD640 chip (not for PCI -- automatically detected) "ide0=qd65xx" : probe/support qd65xx interface "ide0=ali14xx" : probe/support ali14xx chipsets (ALI M1439/M1443/M1445) "ide0=umc8672" : probe/support umc8672 chipsets "ide=doubler" : probe/support IDE doublers on Amiga There may be more options than shown -- use the source, Luke! Everything else is rejected with a "BAD OPTION" message. ================================================================================ IDE ATAPI streaming tape driver ------------------------------- This driver is a part of the Linux ide driver and works in co-operation with linux/drivers/block/ide.c. The driver, in co-operation with ide.c, basically traverses the request-list for the block device interface. The character device interface, on the other hand, creates new requests, adds them to the request-list of the block device, and waits for their completion. Pipelined operation mode is now supported on both reads and writes. The block device major and minor numbers are determined from the tape's relative position in the ide interfaces, as explained in ide.c. The character device interface consists of the following devices: ht0 major 37, minor 0 first IDE tape, rewind on close. ht1 major 37, minor 1 second IDE tape, rewind on close. ... nht0 major 37, minor 128 first IDE tape, no rewind on close. nht1 major 37, minor 129 second IDE tape, no rewind on close. ... Run /dev/MAKEDEV to create the above entries. The general magnetic tape commands compatible interface, as defined by include/linux/mtio.h, is accessible through the character device. General ide driver configuration options, such as the interrupt-unmask flag, can be configured by issuing an ioctl to the block device interface, as any other ide device. Our own ide-tape ioctl's can be issued to either the block device or the character device interface. Maximal throughput with minimal bus load will usually be achieved in the following scenario: 1. ide-tape is operating in the pipelined operation mode. 2. No buffering is performed by the user backup program. ================================================================================ 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 uptions to current ide.c comments at 2.6.0-test4 time. Maciej Soltysiak