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diff --git a/Documentation/ide.txt b/Documentation/ide.txt new file mode 100644 index 000000000..09a969f5c --- /dev/null +++ b/Documentation/ide.txt @@ -0,0 +1,482 @@ +ide.txt -- Information regarding the Enhanced IDE drive in Linux 2.1.xx +=============================================================================== +Supported by: + Mark Lord <mlord@pobox.com> -- disks, interfaces, probing + Gadi Oxman <gadio@netvision.net.il> -- tapes, disks, whatever + Scott Snyder <snyder@fnald0.fnal.gov> -- cdroms, ATAPI, audio + + +-----------------------------------------------------------------+ + | The hdparm utility for controlling various IDE features is | + | packaged separately. Look for it on popular linux FTP sites. | + +-----------------------------------------------------------------+ + +See description later on below for handling BIG IDE drives with >1024 cyls. + +Major features of the 2.1.xx IDE driver ("NEW!" marks changes since 2.0.xx): + +NEW! - support for IDE ATAPI *floppy* drives + - support for IDE ATAPI *tape* drives, courtesy of Gadi Oxman + (re-run MAKEDEV.ide to create the tape device entries in /dev/) + - support for up to *four* IDE interfaces on one or more IRQs + - support for any mix of up to *eight* IDE drives + - support for reading IDE ATAPI cdrom drives (NEC,MITSUMI,VERTOS,SONY) + - support for audio functions + - auto-detection of interfaces, drives, IRQs, and disk geometries + - "single" drives should be jumpered as "master", not "slave" + (both are now probed for) + - support for BIOSs which report "more than 16 heads" on disk drives + - uses LBA (slightly faster) on disk drives which support it + - support for lots of fancy (E)IDE drive functions with hdparm utility + - optional (compile time) support for 32-bit VLB data transfers + - support for IDE multiple (block) mode (same as hd.c) + - support for interrupt unmasking during I/O (better than hd.c) + - improved handshaking and error detection/recovery + - can co-exist with hd.c controlling the first interface + - run-time selectable 32bit interface support (using hdparm-2.3) + - support for reliable operation of buggy RZ1000 interfaces + - PCI support is automatic when rz1000 support is configured + - support for reliable operation of buggy CMD-640 interfaces + - PCI support is automatic when cmd640 support is configured + - for VLB, use kernel command line option: ide0=cmd640_vlb + - this support also enables the secondary i/f when needed + - interface PIO timing & prefetch parameter support + - experimental support for UMC 8672 interfaces + - support for secondary interface on the FGI/Holtek HT-6560B VLB i/f + - use kernel command line option: ide0=ht6560 + - experimental support for various IDE chipsets + - use appropriate kernel command line option from list below + - support for drives with a stuck WRERR_STAT bit + - support for removable devices, including door lock/unlock + - transparent support for DiskManager 6.0x and "Dynamic Disk Overlay" + - works with Linux fdisk, LILO, loadlin, bootln, etc.. + - mostly transparent support for EZ-Drive disk translation software + - to use LILO with EZ, install LILO on the linux partition + rather than on the master boot record, and then mark the + linux partition as "bootable" or "active" using fdisk. + (courtesy of Juha Laiho <jlaiho@ichaos.nullnet.fi>). + - auto-detect of disk translations by examining partition table + - ide-cd.c now compiles separate from ide.c + - Bus-Master DMA support for Intel PCI Triton chipset IDE interfaces + - for details, see comments at top of triton.c + - ide-cd.c now supports door locking and auto-loading. + - Also preliminary support for multisession + and direct reads of audio data. + - experimental support for Promise DC4030VL caching interface card + - email thanks/problems to: peterd@pnd-pc.demon.co.uk + - the hdparm-3.1 package can be used to set PIO modes for some chipsets. +NEW! - support for the OPTi 82C621 chipset, courtesy of Jaromir Koutek. +NEW! - support for loadable modules + + +For work in progress, see the comments in ide.c, ide-cd.c, triton.c, ... + +*** 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. + +This is the multiple IDE interface driver, as evolved from hd.c. +It supports up to four IDE interfaces, on one or more IRQs (usually 14 & 15). +There can be up to two drives per interface, as per the ATA-2 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 + +To access devices on the 2nd/3rd/4th interfaces, device entries must first be +created in /dev for them. To create such entries, simply run the included +shell script: /usr/src/linux/scripts/MAKEDEV.ide + +Apparently many releases of Slackware 2.2/2.3 have incorrect entries +in /dev for hdc* and hdd* -- this can also be corrected by running MAKEDEV.ide + +ide.c automatically probes for the primary and secondary interfaces, +for the drives/geometries attached to those interfaces, and for the +IRQ numbers being used by the interfaces (normally IRQ14 & IRQ15). + +Interfaces beyond the first two are not normally probed for, but 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 ide.c now probes for both units, though success is more likely +when the drive is jumpered correctly. + +Courtesy of Scott Snyder, 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 harddisk. + +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 harddrive 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 /cd + mount /dev/cdrom /cd -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 the cdrom stuff to the author & maintainer, +Scott Snyder (snyder@fnald0.fnal.gov). + +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 + +mlord@pobox.com +snyder@fnald0.fnal.gov +================================================================================ + +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=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=slow" : insert a huge pause after each access to the data + port. Should be used only as a last resort. + + "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 and ide(x^1) + + The following are valid ONLY on ide0, + 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=qd6580" : probe/support qd6580 interface + "ide0=ali14xx" : probe/support ali14xx chipsets (ALI M1439/M1445) + "ide0=umc8672" : probe/support umc8672 chipsets + +Everything else is rejected with a "BAD OPTION" message. + +================================================================================ + +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". + +IDE drives are designed to attach almost directly to the ISA bus of an AT-style +computer. The typical IDE interface card merely provides I/O port address +decoding and tri-state buffers, although several newer localbus cards go much +beyond the basics. When purchasing a localbus IDE interface, avoid cards with +an onboard BIOS and those which require special drivers. Instead, look for a +card which uses hardware switches/jumpers to select the interface timing speed, +to allow much faster data transfers than the original 8MHz ISA bus allows. + +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-2 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 and TAPE devices, and will +likely also soon be used for Floppy drives, removable R/W cartridges, +and for high capacity hard disk drives. + +How To Use *Big* ATA/IDE drives with Linux +------------------------------------------ +The ATA Interface spec for IDE disk drives allows a total of 28 bits +(8 bits for sector, 16 bits for cylinder, and 4 bits for head) for addressing +individual disk sectors of 512 bytes each (in "Linear Block Address" (LBA) +mode, there is still only a total of 28 bits available in the hardware). +This "limits" the capacity of an IDE drive to no more than 128GB (Giga-bytes). +All current day IDE drives are somewhat smaller than this upper limit, and +within a few years, ATAPI disk drives will raise the limit considerably. + +All IDE disk drives "suffer" from a "16-heads" limitation: the hardware has +only a four bit field for head selection, restricting the number of "physical" +heads to 16 or less. Since the BIOS usually has a 63 sectors/track limit, +this means that all IDE drivers larger than 504MB (528Meg) must use a "physical" +geometry with more than 1024 cylinders. + + (1024cyls * 16heads * 63sects * 512bytes/sector) / (1024 * 1024) == 504MB + +(Some BIOSs (and controllers with onboard BIOS) pretend to allow "32" or "64" + heads per drive (discussed below), but can only do so by playing games with + the real (hidden) geometry, which is always limited to 16 or fewer heads). + +This presents two problems to most systems: + + 1. The INT13 interface to the BIOS only allows 10-bits for cylinder + addresses, giving a limit of 1024cyls for programs which use it. + + 2. The physical geometry fields of the disk partition table only + allow 10-bits for cylinder addresses, giving a similar limit of 1024 + cyls for operating systems that do not use the "sector count" fields + instead of the physical Cyl/Head/Sect (CHS) geometry fields. + +Neither of these limitations affects Linux itself, as it (1) does not use the +BIOS for disk access, and it (2) is clever enough to use the "sector count" +fields of the partition table instead of the physical CHS geometry fields. + + a) Most folks use LILO to load linux. LILO uses the INT13 interface + to the BIOS to load the kernel at boot time. Therefore, LILO can only + load linux if the files it needs (usually just the kernel images) are + located below the magic 1024 cylinder "boundary" (more on this later). + + b) Many folks also like to have bootable DOS partitions on their + drive(s). DOS also uses the INT13 interface to the BIOS, not only + for booting, but also for operation after booting. Therefore, DOS + can normally only access partitions which are contained entirely below + the magic 1024 cylinder "boundary". + +There are at least seven commonly used schemes for kludging DOS to work +around this "limitation". In the long term, the problem is being solved +by introduction of an alternative BIOS interface that does not have the +same limitations as the INT13 interface. New versions of DOS are expected +to detect and use this interface in systems whose BIOS provides it. + +But in the present day, alternative solutions are necessary. + +The most popular solution in newer systems is to have the BIOS shift bits +between the cylinder and head number fields. This is activated by entering +a translated logical geometry into the BIOS/CMOS setup for the drive. +Thus, if the drive has a geometry of 2100/16/63 (CHS), then the BIOS could +present a "logical" geometry of 525/64/63 by "shifting" two bits from the +cylinder number into the head number field for purposes of the partition table, +CMOS setup, and INT13 interfaces. Linux kernels 1.1.39 and higher detect and +"handle" this translation automatically, making this a rather painless solution +for the 1024 cyls problem. If for some reason Linux gets confused (unlikely), +then use the kernel command line parameters to pass the *logical* geometry, +as in: hda=525,64,63 + +If the BIOS does not support this form of drive translation, then several +options remain, listed below in order of popularity: + + - use a partition below the 1024 cyl boundary to hold the linux + boot files (kernel images and /boot directory), and place the rest + of linux anywhere else on the drive. These files can reside in a DOS + partition, or in a tailor-made linux boot partition. + - use DiskManager software from OnTrack, supplied free with + many new hard drive purchases. + - use EZ-Drive software (similar to DiskManager). Note though, + that LILO must *not* use the MBR when EZ-Drive is present. + Instead, install LILO on the first sector of your linux partition, + and mark it as "active" or "bootable" with fdisk. + - boot from a floppy disk instead of the hard drive (takes 10 seconds). + +If you cannot use drive translation, *and* your BIOS also restricts you to +entering no more than 1024 cylinders in the geometry field in the CMOS setup, +then just set it to 1024. As of v3.5 of this driver, Linux automatically +determines the *real* number of cylinders for fdisk to use, allowing easy +access to the full disk capacity without having to fiddle around. + +Regardless of what you do, all DOS partitions *must* be contained entirely +within the first 1024 logical cylinders. For a 1Gig WD disk drive, here's +a good "half and half" partitioning scheme to start with: + + geometry = 2100/16/63 + /dev/hda1 from cyl 1 to 992 dos + /dev/hda2 from cyl 993 to 1023 swap + /dev/hda3 from cyl 1024 to 2100 linux + +To ensure that LILO can boot linux, the boot files (kernel and /boot/*) +must reside within the first 1024 cylinders of the drive. If your linux +root partition is *not* completely within the first 1024 cyls (quite common), +then you can use LILO to boot linux from files on your DOS partition +by doing the following after installing slackware (or whatever): + + 0. Boot from the "boot floppy" created during the installation + 1. Mount your DOS partition as /dos (and stick it in /etc/fstab) + 2. Move your kernel (/vmlinuz) to /dos/vmlinuz with: mv /vmlinuz /dos + 3. Edit /etc/lilo.conf to change /vmlinuz to /dos/vmlinuz + 4. Move /boot to /dos/boot with: cp -a /boot /dos ; rm -r /boot + 5. Create a symlink for LILO to use with: ln -s /dos/boot /boot + 6. Re-run LILO with: lilo + + A danger with this approach is that whenever an MS-DOS "defragmentation" + program is run (like Norton "speeddisk"), it may move the Linux boot + files around, confusing LILO and making the (Linux) system unbootable. + Be sure to keep a kernel "boot floppy" at hand for such circumstances. + A possible workaround is to mark the Linux files as S+H+R (System, + Hidden, Readonly), to prevent most defragmentation programs from + moving the files around. + +If you "don't do DOS", then partition as you please, but remember to create +a small partition to hold the /boot directory (and vmlinuz) as described above +such that they stay within the first 1024 cylinders. + +Note that when creating partitions that span beyond cylinder 1024, +Linux fdisk will complain about "Partition X has different physical/logical +endings" and emit messages such as "This is larger than 1024, and may cause +problems with some software". Ignore this for linux partitions. The "some +software" refers to DOS, the BIOS, and LILO, as described previously. + +Western Digital ships a "DiskManager 6.03" diskette with all of their big +hard drives. Use BIOS translation instead of this if possible, as it is a +more generally compatible method of achieving the same results (DOS access +to the entire disk). However, if you must use DiskManager, it now works +with Linux 1.3.x in most cases. Let me know if you still have trouble. + +My recommendations to anyone who asks about NEW systems are: + + - buy a motherboard that uses the Intel Triton chipset -- very common. + - use IDE for the first two drives, placing them on separate interfaces. + - place the IDE cdrom drive as slave on either interface. + - if additional disks are to be connected, consider your needs: + - fileserver? Buy a SC200 SCSI adaptor for the next few drives. + - personal system? Use IDE for the next two drives. + - still not enough? Keep adding SC200 SCSI cards as needed. + +Most manufacturers make both IDE and SCSI-2 versions of each of their drives. +The IDE ones are usually faster and cheaper, due to the higher data transfer +speed of PIO mode4 (ATA2), 16.6MBytes/sec versus 10Mbytes/sec for SCSI-2. + +In particular, I recommend Quantum FireBalls as cheap and exceptionally fast. +The new WD1.6GB models are also cheap screamers. + +For really high end systems, go for fast/wide 7200rpm SCSI. But it'll cost ya! + +mlord@pobox.com |