patch-pre2.0.2 linux/Documentation/ide.txt

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+ide.txt -- Information regarding the Enhanced IDE drive in Linux 2.0.x
+===============================================================================
+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 ide.c & ide-cd.c ("NEW!" marks changes since 1.2.13):
+
+NEW!	- support for IDE ATAPI *tape* drives, courtesy of Gadi Oxman
+		(re-run MAKEDEV.ide to create the tape device entries in /dev/)
+NEW!	- support for up to *four* IDE interfaces on one or more IRQs
+NEW!	- support for any mix of up to *eight* disk and/or cdrom 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"
+NEW!		  (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)
+NEW!	- support for reliable operation of buggy RZ1000 interfaces
+		- PCI support is automatic when rz1000 support is configured
+NEW!	- 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 on most cards
+		- experimental interface timing parameter support
+NEW!	- experimental support for UMC 8672 interfaces
+NEW!	- support for secondary interface on the FGI/Holtek HT-6560B VLB i/f
+		- use kernel command line option:   ide0=ht6560
+NEW!	- experimental support for various IDE chipsets
+		- use appropriate kernel command line option from list below
+NEW!	- support for drives with a stuck WRERR_STAT bit
+NEW!	- support for removable devices, including door lock/unlock
+NEW!	- transparent support for DiskManager 6.0x and "Dynamic Disk Overlay"
+	- works with Linux fdisk, LILO, loadlin, bootln, etc..
+NEW!	- mostly transparent support for EZ-Drive disk translation software
+NEW!		- 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>).
+NEW!	- auto-detect of disk translations by examining partition table
+NEW!	- ide-cd.c now compiles separate from ide.c
+NEW!	- Bus-Master DMA support for Intel PCI Triton chipset IDE interfaces
+		- for details, see comments at top of triton.c
+NEW!    - ide-cd.c now supports door locking and auto-loading.
+		- Also preliminary support for multisession
+		  and direct reads of audio data.
+NEW!	- experimental support for Promise DC4030VL caching interface card
+NEW!		- email thanks/problems to: peterd@pnd-pc.demon.co.uk
+NEW!	- the hdparm-2.7 package can be used to set PIO modes for some chipsets.
+
+For work in progress, see the comments in ide.c, ide-cd.c, and triton.c.
+
+Note that there is now a group actively working on support for the Promise
+caching IDE cards, such as the DC4030VL, and early results are encouraging.
+Look for this support to be added to the kernel soon.
+
+
+***  IMPORTANT NOTICES (for kernel versions after 1.3.21)
+***  =================
+***  PCI versions of the CMD640 and RZ1000 interfaces are now detected
+***  automatically at startup when PCI BIOS support is configured.
+***  Linux disables the "pre-fetch" or "read-ahead" modes of these interfaces
+***  to prevent data corruption possible due to hardware design flaws.
+***  Use of the "serialize" option is no longer necessary.
+***
+***  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 0x???; major=33; hde is minor=0; hdf is minor=64
+Quaternary: ide3, port 0x???; 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=0x1e8,0x3f0,11	/* ioports 0x1e8-0x1ef,0x3f0, irq 11 */
+
+Normally the irq number need not be specified, as ide.c will probe for it:
+
+	ide3=0x1e8,0x3f0	/* ioports 0x1e8-0x1ef,0x3f0 */
+
+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.
+
+ "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
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen, slshen@lbl.gov with Sam's (original) version
of this