1============================================
2Information regarding the Enhanced IDE drive
3============================================
4
5   The hdparm utility can be used to control various IDE features on a
6   running system. It is packaged separately.  Please Look for it on popular
7   linux FTP sites.
8
9-------------------------------------------------------------------------------
10
11.. important::
12
13   BUGGY IDE CHIPSETS CAN CORRUPT DATA!!
14
15    PCI versions of the CMD640 and RZ1000 interfaces are now detected
16    automatically at startup when PCI BIOS support is configured.
17
18    Linux disables the "prefetch" ("readahead") mode of the RZ1000
19    to prevent data corruption possible due to hardware design flaws.
20
21    For the CMD640, linux disables "IRQ unmasking" (hdparm -u1) on any
22    drive for which the "prefetch" mode of the CMD640 is turned on.
23    If "prefetch" is disabled (hdparm -p8), then "IRQ unmasking" can be
24    used again.
25
26    For the CMD640, linux disables "32bit I/O" (hdparm -c1) on any drive
27    for which the "prefetch" mode of the CMD640 is turned off.
28    If "prefetch" is enabled (hdparm -p9), then "32bit I/O" can be
29    used again.
30
31    The CMD640 is also used on some Vesa Local Bus (VLB) cards, and is *NOT*
32    automatically detected by Linux.  For safe, reliable operation with such
33    interfaces, one *MUST* use the "cmd640.probe_vlb" kernel option.
34
35    Use of the "serialize" option is no longer necessary.
36
37-------------------------------------------------------------------------------
38
39Common pitfalls
40===============
41
42- 40-conductor IDE cables are capable of transferring data in DMA modes up to
43  udma2, but no faster.
44
45- If possible devices should be attached to separate channels if they are
46  available. Typically the disk on the first and CD-ROM on the second.
47
48- If you mix devices on the same cable, please consider using similar devices
49  in respect of the data transfer mode they support.
50
51- Even better try to stick to the same vendor and device type on the same
52  cable.
53
54This is the multiple IDE interface driver, as evolved from hd.c
55===============================================================
56
57It supports up to 9 IDE interfaces per default, on one or more IRQs (usually
5814 & 15).  There can be up to two drives per interface, as per the ATA-6 spec.::
59
60  Primary:    ide0, port 0x1f0; major=3;  hda is minor=0; hdb is minor=64
61  Secondary:  ide1, port 0x170; major=22; hdc is minor=0; hdd is minor=64
62  Tertiary:   ide2, port 0x1e8; major=33; hde is minor=0; hdf is minor=64
63  Quaternary: ide3, port 0x168; major=34; hdg is minor=0; hdh is minor=64
64  fifth..     ide4, usually PCI, probed
65  sixth..     ide5, usually PCI, probed
66
67To access devices on interfaces > ide0, device entries please make sure that
68device files for them are present in /dev.  If not, please create such
69entries, by using /dev/MAKEDEV.
70
71This driver automatically probes for most IDE interfaces (including all PCI
72ones), for the drives/geometries attached to those interfaces, and for the IRQ
73lines being used by the interfaces (normally 14, 15 for ide0/ide1).
74
75Any number of interfaces may share a single IRQ if necessary, at a slight
76performance penalty, whether on separate cards or a single VLB card.
77The IDE driver automatically detects and handles this.  However, this may
78or may not be harmful to your hardware.. two or more cards driving the same IRQ
79can potentially burn each other's bus driver, though in practice this
80seldom occurs.  Be careful, and if in doubt, don't do it!
81
82Drives are normally found by auto-probing and/or examining the CMOS/BIOS data.
83For really weird situations, the apparent (fdisk) geometry can also be specified
84on the kernel "command line" using LILO.  The format of such lines is::
85
86	ide_core.chs=[interface_number.device_number]:cyls,heads,sects
87
88or::
89
90	ide_core.cdrom=[interface_number.device_number]
91
92For example::
93
94	ide_core.chs=1.0:1050,32,64  ide_core.cdrom=1.1
95
96The results of successful auto-probing may override the physical geometry/irq
97specified, though the "original" geometry may be retained as the "logical"
98geometry for partitioning purposes (fdisk).
99
100If the auto-probing during boot time confuses a drive (ie. the drive works
101with hd.c but not with ide.c), then an command line option may be specified
102for each drive for which you'd like the drive to skip the hardware
103probe/identification sequence.  For example::
104
105	ide_core.noprobe=0.1
106
107or::
108
109	ide_core.chs=1.0:768,16,32
110	ide_core.noprobe=1.0
111
112Note that when only one IDE device is attached to an interface, it should be
113jumpered as "single" or "master", *not* "slave".  Many folks have had
114"trouble" with cdroms because of this requirement, so the driver now probes
115for both units, though success is more likely when the drive is jumpered
116correctly.
117
118Courtesy of Scott Snyder and others, the driver supports ATAPI cdrom drives
119such as the NEC-260 and the new MITSUMI triple/quad speed drives.
120Such drives will be identified at boot time, just like a hard disk.
121
122If for some reason your cdrom drive is *not* found at boot time, you can force
123the probe to look harder by supplying a kernel command line parameter
124via LILO, such as:::
125
126	ide_core.cdrom=1.0	/* "master" on second interface (hdc) */
127
128or::
129
130	ide_core.cdrom=1.1	/* "slave" on second interface (hdd) */
131
132For example, a GW2000 system might have a hard drive on the primary
133interface (/dev/hda) and an IDE cdrom drive on the secondary interface
134(/dev/hdc).  To mount a CD in the cdrom drive, one would use something like::
135
136	ln -sf /dev/hdc /dev/cdrom
137	mkdir /mnt/cdrom
138	mount /dev/cdrom /mnt/cdrom -t iso9660 -o ro
139
140If, after doing all of the above, mount doesn't work and you see
141errors from the driver (with dmesg) complaining about `status=0xff`,
142this means that the hardware is not responding to the driver's attempts
143to read it.  One of the following is probably the problem:
144
145  - Your hardware is broken.
146
147  - You are using the wrong address for the device, or you have the
148    drive jumpered wrong.  Review the configuration instructions above.
149
150  - Your IDE controller requires some nonstandard initialization sequence
151    before it will work properly.  If this is the case, there will often
152    be a separate MS-DOS driver just for the controller.  IDE interfaces
153    on sound cards usually fall into this category.  Such configurations
154    can often be made to work by first booting MS-DOS, loading the
155    appropriate drivers, and then warm-booting linux (without powering
156    off).  This can be automated using loadlin in the MS-DOS autoexec.
157
158If you always get timeout errors, interrupts from the drive are probably
159not making it to the host.  Check how you have the hardware jumpered
160and make sure it matches what the driver expects (see the configuration
161instructions above).  If you have a PCI system, also check the BIOS
162setup; I've had one report of a system which was shipped with IRQ 15
163disabled by the BIOS.
164
165The kernel is able to execute binaries directly off of the cdrom,
166provided it is mounted with the default block size of 1024 (as above).
167
168Please pass on any feedback on any of this stuff to the maintainer,
169whose address can be found in linux/MAINTAINERS.
170
171The IDE driver is modularized.  The high level disk/CD-ROM/tape/floppy
172drivers can always be compiled as loadable modules, the chipset drivers
173can only be compiled into the kernel, and the core code (ide.c) can be
174compiled as a loadable module provided no chipset support is needed.
175
176When using ide.c as a module in combination with kmod, add::
177
178	alias block-major-3 ide-probe
179
180to a configuration file in /etc/modprobe.d/.
181
182When ide.c is used as a module, you can pass command line parameters to the
183driver using the "options=" keyword to insmod, while replacing any ',' with
184';'.
185
186
187Summary of ide driver parameters for kernel command line
188========================================================
189
190For legacy IDE VLB host drivers (ali14xx/dtc2278/ht6560b/qd65xx/umc8672)
191you need to explicitly enable probing by using "probe" kernel parameter,
192i.e. to enable probing for ALI M14xx chipsets (ali14xx host driver) use:
193
194* "ali14xx.probe" boot option when ali14xx driver is built-in the kernel
195
196* "probe" module parameter when ali14xx driver is compiled as module
197  ("modprobe ali14xx probe")
198
199Also for legacy CMD640 host driver (cmd640) you need to use "probe_vlb"
200kernel paremeter to enable probing for VLB version of the chipset (PCI ones
201are detected automatically).
202
203You also need to use "probe" kernel parameter for ide-4drives driver
204(support for IDE generic chipset with four drives on one port).
205
206To enable support for IDE doublers on Amiga use "doubler" kernel parameter
207for gayle host driver (i.e. "gayle.doubler" if the driver is built-in).
208
209To force ignoring cable detection (this should be needed only if you're using
210short 40-wires cable which cannot be automatically detected - if this is not
211a case please report it as a bug instead) use "ignore_cable" kernel parameter:
212
213* "ide_core.ignore_cable=[interface_number]" boot option if IDE is built-in
214  (i.e. "ide_core.ignore_cable=1" to force ignoring cable for "ide1")
215
216* "ignore_cable=[interface_number]" module parameter (for ide_core module)
217  if IDE is compiled as module
218
219Other kernel parameters for ide_core are:
220
221* "nodma=[interface_number.device_number]" to disallow DMA for a device
222
223* "noflush=[interface_number.device_number]" to disable flush requests
224
225* "nohpa=[interface_number.device_number]" to disable Host Protected Area
226
227* "noprobe=[interface_number.device_number]" to skip probing
228
229* "nowerr=[interface_number.device_number]" to ignore the WRERR_STAT bit
230
231* "cdrom=[interface_number.device_number]" to force device as a CD-ROM
232
233* "chs=[interface_number.device_number]" to force device as a disk (using CHS)
234
235
236Some Terminology
237================
238
239IDE
240  Integrated Drive Electronics, meaning that each drive has a built-in
241  controller, which is why an "IDE interface card" is not a "controller card".
242
243ATA
244  AT (the old IBM 286 computer) Attachment Interface, a draft American
245  National Standard for connecting hard drives to PCs.  This is the official
246  name for "IDE".
247
248  The latest standards define some enhancements, known as the ATA-6 spec,
249  which grew out of vendor-specific "Enhanced IDE" (EIDE) implementations.
250
251ATAPI
252  ATA Packet Interface, a new protocol for controlling the drives,
253  similar to SCSI protocols, created at the same time as the ATA2 standard.
254  ATAPI is currently used for controlling CDROM, TAPE and FLOPPY (ZIP or
255  LS120/240) devices, removable R/W cartridges, and for high capacity hard disk
256  drives.
257
258mlord@pobox.com
259
260
261Wed Apr 17 22:52:44 CEST 2002 edited by Marcin Dalecki, the current
262maintainer.
263
264Wed Aug 20 22:31:29 CEST 2003 updated ide boot options to current ide.c
265comments at 2.6.0-test4 time. Maciej Soltysiak <solt@dns.toxicfilms.tv>
266