390 lines
15 KiB
Plaintext
390 lines
15 KiB
Plaintext
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Information regarding the Enhanced IDE drive in Linux 2.6
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==============================================================================
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The hdparm utility can be used to control various IDE features on a
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running system. It is packaged separately. Please Look for it on popular
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linux FTP sites.
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*** IMPORTANT NOTICES: BUGGY IDE CHIPSETS CAN CORRUPT DATA!!
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*** =================
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*** PCI versions of the CMD640 and RZ1000 interfaces are now detected
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*** automatically at startup when PCI BIOS support is configured.
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***
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*** Linux disables the "prefetch" ("readahead") mode of the RZ1000
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*** to prevent data corruption possible due to hardware design flaws.
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***
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*** For the CMD640, linux disables "IRQ unmasking" (hdparm -u1) on any
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*** drive for which the "prefetch" mode of the CMD640 is turned on.
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*** If "prefetch" is disabled (hdparm -p8), then "IRQ unmasking" can be
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*** used again.
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***
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*** For the CMD640, linux disables "32bit I/O" (hdparm -c1) on any drive
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*** for which the "prefetch" mode of the CMD640 is turned off.
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*** If "prefetch" is enabled (hdparm -p9), then "32bit I/O" can be
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*** used again.
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***
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*** The CMD640 is also used on some Vesa Local Bus (VLB) cards, and is *NOT*
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*** automatically detected by Linux. For safe, reliable operation with such
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*** interfaces, one *MUST* use the "ide0=cmd640_vlb" kernel option.
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***
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*** Use of the "serialize" option is no longer necessary.
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================================================================================
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Common pitfalls:
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- 40-conductor IDE cables are capable of transferring data in DMA modes up to
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udma2, but no faster.
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- If possible devices should be attached to separate channels if they are
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available. Typically the disk on the first and CD-ROM on the second.
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- If you mix devices on the same cable, please consider using similar devices
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in respect of the data transfer mode they support.
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- Even better try to stick to the same vendor and device type on the same
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cable.
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================================================================================
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This is the multiple IDE interface driver, as evolved from hd.c.
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It supports up to 9 IDE interfaces per default, on one or more IRQs (usually
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14 & 15). There can be up to two drives per interface, as per the ATA-6 spec.
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Primary: ide0, port 0x1f0; major=3; hda is minor=0; hdb is minor=64
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Secondary: ide1, port 0x170; major=22; hdc is minor=0; hdd is minor=64
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Tertiary: ide2, port 0x1e8; major=33; hde is minor=0; hdf is minor=64
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Quaternary: ide3, port 0x168; major=34; hdg is minor=0; hdh is minor=64
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fifth.. ide4, usually PCI, probed
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sixth.. ide5, usually PCI, probed
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To access devices on interfaces > ide0, device entries please make sure that
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device files for them are present in /dev. If not, please create such
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entries, by using /dev/MAKEDEV.
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This driver automatically probes for most IDE interfaces (including all PCI
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ones), for the drives/geometries attached to those interfaces, and for the IRQ
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lines being used by the interfaces (normally 14, 15 for ide0/ide1).
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For special cases, interfaces may be specified using kernel "command line"
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options. For example,
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ide3=0x168,0x36e,10 /* ioports 0x168-0x16f,0x36e, irq 10 */
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Normally the irq number need not be specified, as ide.c will probe for it:
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ide3=0x168,0x36e /* ioports 0x168-0x16f,0x36e */
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The standard port, and irq values are these:
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ide0=0x1f0,0x3f6,14
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ide1=0x170,0x376,15
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ide2=0x1e8,0x3ee,11
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ide3=0x168,0x36e,10
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Note that the first parameter reserves 8 contiguous ioports, whereas the
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second value denotes a single ioport. If in doubt, do a 'cat /proc/ioports'.
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In all probability the device uses these ports and IRQs if it is attached
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to the appropriate ide channel. Pass the parameter for the correct ide
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channel to the kernel, as explained above.
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Any number of interfaces may share a single IRQ if necessary, at a slight
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performance penalty, whether on separate cards or a single VLB card.
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The IDE driver automatically detects and handles this. However, this may
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or may not be harmful to your hardware.. two or more cards driving the same IRQ
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can potentially burn each other's bus driver, though in practice this
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seldom occurs. Be careful, and if in doubt, don't do it!
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Drives are normally found by auto-probing and/or examining the CMOS/BIOS data.
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For really weird situations, the apparent (fdisk) geometry can also be specified
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on the kernel "command line" using LILO. The format of such lines is:
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hdx=cyls,heads,sects,wpcom,irq
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or hdx=cdrom
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where hdx can be any of hda through hdh, Three values are required
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(cyls,heads,sects). For example:
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hdc=1050,32,64 hdd=cdrom
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either {hda,hdb} or {hdc,hdd}. The results of successful auto-probing may
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override the physical geometry/irq specified, though the "original" geometry
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may be retained as the "logical" geometry for partitioning purposes (fdisk).
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If the auto-probing during boot time confuses a drive (ie. the drive works
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with hd.c but not with ide.c), then an command line option may be specified
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for each drive for which you'd like the drive to skip the hardware
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probe/identification sequence. For example:
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hdb=noprobe
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or
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hdc=768,16,32
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hdc=noprobe
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Note that when only one IDE device is attached to an interface, it should be
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jumpered as "single" or "master", *not* "slave". Many folks have had
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"trouble" with cdroms because of this requirement, so the driver now probes
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for both units, though success is more likely when the drive is jumpered
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correctly.
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Courtesy of Scott Snyder and others, the driver supports ATAPI cdrom drives
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such as the NEC-260 and the new MITSUMI triple/quad speed drives.
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Such drives will be identified at boot time, just like a hard disk.
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If for some reason your cdrom drive is *not* found at boot time, you can force
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the probe to look harder by supplying a kernel command line parameter
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via LILO, such as:
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hdc=cdrom /* hdc = "master" on second interface */
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or
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hdd=cdrom /* hdd = "slave" on second interface */
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For example, a GW2000 system might have a hard drive on the primary
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interface (/dev/hda) and an IDE cdrom drive on the secondary interface
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(/dev/hdc). To mount a CD in the cdrom drive, one would use something like:
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ln -sf /dev/hdc /dev/cdrom
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mkdir /mnt/cdrom
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mount /dev/cdrom /mnt/cdrom -t iso9660 -o ro
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If, after doing all of the above, mount doesn't work and you see
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errors from the driver (with dmesg) complaining about `status=0xff',
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this means that the hardware is not responding to the driver's attempts
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to read it. One of the following is probably the problem:
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- Your hardware is broken.
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- You are using the wrong address for the device, or you have the
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drive jumpered wrong. Review the configuration instructions above.
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- Your IDE controller requires some nonstandard initialization sequence
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before it will work properly. If this is the case, there will often
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be a separate MS-DOS driver just for the controller. IDE interfaces
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on sound cards usually fall into this category. Such configurations
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can often be made to work by first booting MS-DOS, loading the
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appropriate drivers, and then warm-booting linux (without powering
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off). This can be automated using loadlin in the MS-DOS autoexec.
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If you always get timeout errors, interrupts from the drive are probably
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not making it to the host. Check how you have the hardware jumpered
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and make sure it matches what the driver expects (see the configuration
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instructions above). If you have a PCI system, also check the BIOS
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setup; I've had one report of a system which was shipped with IRQ 15
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disabled by the BIOS.
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The kernel is able to execute binaries directly off of the cdrom,
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provided it is mounted with the default block size of 1024 (as above).
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Please pass on any feedback on any of this stuff to the maintainer,
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whose address can be found in linux/MAINTAINERS.
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Note that if BOTH hd.c and ide.c are configured into the kernel,
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hd.c will normally be allowed to control the primary IDE interface.
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This is useful for older hardware that may be incompatible with ide.c,
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and still allows newer hardware to run on the 2nd/3rd/4th IDE ports
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under control of ide.c. To have ide.c also "take over" the primary
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IDE port in this situation, use the "command line" parameter: ide0=0x1f0
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The IDE driver is modularized. The high level disk/CD-ROM/tape/floppy
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drivers can always be compiled as loadable modules, the chipset drivers
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can only be compiled into the kernel, and the core code (ide.c) can be
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compiled as a loadable module provided no chipset support is needed.
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When using ide.c as a module in combination with kmod, add:
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alias block-major-3 ide-probe
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to /etc/modprobe.conf.
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When ide.c is used as a module, you can pass command line parameters to the
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driver using the "options=" keyword to insmod, while replacing any ',' with
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';'. For example:
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insmod ide.o options="ide0=serialize ide1=serialize ide2=0x1e8;0x3ee;11"
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================================================================================
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Summary of ide driver parameters for kernel command line
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--------------------------------------------------------
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"hdx=" is recognized for all "x" from "a" to "h", such as "hdc".
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"idex=" is recognized for all "x" from "0" to "3", such as "ide1".
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"hdx=noprobe" : drive may be present, but do not probe for it
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"hdx=none" : drive is NOT present, ignore cmos and do not probe
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"hdx=nowerr" : ignore the WRERR_STAT bit on this drive
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"hdx=cdrom" : drive is present, and is a cdrom drive
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"hdx=cyl,head,sect" : disk drive is present, with specified geometry
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"hdx=remap" : remap access of sector 0 to sector 1 (for EZDrive)
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"hdx=remap63" : remap the drive: add 63 to all sector numbers
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(for DM OnTrack)
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"idex=noautotune" : driver will NOT attempt to tune interface speed
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"hdx=autotune" : driver will attempt to tune interface speed
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to the fastest PIO mode supported,
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if possible for this drive only.
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Not fully supported by all chipset types,
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and quite likely to cause trouble with
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older/odd IDE drives.
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"hdx=swapdata" : when the drive is a disk, byte swap all data
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"hdx=bswap" : same as above..........
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"hdx=scsi" : the return of the ide-scsi flag, this is useful for
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allowing ide-floppy, ide-tape, and ide-cdrom|writers
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to use ide-scsi emulation on a device specific option.
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"idebus=xx" : inform IDE driver of VESA/PCI bus speed in MHz,
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where "xx" is between 20 and 66 inclusive,
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used when tuning chipset PIO modes.
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For PCI bus, 25 is correct for a P75 system,
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30 is correct for P90,P120,P180 systems,
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and 33 is used for P100,P133,P166 systems.
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If in doubt, use idebus=33 for PCI.
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As for VLB, it is safest to not specify it.
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Bigger values are safer than smaller ones.
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"idex=noprobe" : do not attempt to access/use this interface
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"idex=base" : probe for an interface at the addr specified,
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where "base" is usually 0x1f0 or 0x170
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and "ctl" is assumed to be "base"+0x206
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"idex=base,ctl" : specify both base and ctl
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"idex=base,ctl,irq" : specify base, ctl, and irq number
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"idex=serialize" : do not overlap operations on idex. Please note
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that you will have to specify this option for
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both the respective primary and secondary channel
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to take effect.
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"idex=four" : four drives on idex and ide(x^1) share same ports
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"idex=reset" : reset interface after probe
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"idex=dma" : automatically configure/use DMA if possible.
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"idex=ata66" : informs the interface that it has an 80c cable
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for chipsets that are ATA-66 capable, but the
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ability to bit test for detection is currently
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unknown.
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"ide=reverse" : formerly called to pci sub-system, but now local.
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"ide=nodma" : disable DMA globally for the IDE subsystem.
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The following are valid ONLY on ide0, which usually corresponds
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to the first ATA interface found on the particular host, and the defaults for
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the base,ctl ports must not be altered.
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"ide0=cmd640_vlb" : *REQUIRED* for VLB cards with the CMD640 chip
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(not for PCI -- automatically detected)
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"ide=doubler" : probe/support IDE doublers on Amiga
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There may be more options than shown -- use the source, Luke!
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Everything else is rejected with a "BAD OPTION" message.
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For legacy IDE VLB host drivers (ali14xx/dtc2278/ht6560b/qd65xx/umc8672)
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you need to explicitly enable probing by using "probe" kernel parameter,
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i.e. to enable probing for ALI M14xx chipsets (ali14xx host driver) use:
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* "ali14xx.probe" boot option when ali14xx driver is built-in the kernel
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* "probe" module parameter when ali14xx driver is compiled as module
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("modprobe ali14xx probe")
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================================================================================
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IDE ATAPI streaming tape driver
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-------------------------------
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This driver is a part of the Linux ide driver and works in co-operation
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with linux/drivers/block/ide.c.
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The driver, in co-operation with ide.c, basically traverses the
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request-list for the block device interface. The character device
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interface, on the other hand, creates new requests, adds them
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to the request-list of the block device, and waits for their completion.
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Pipelined operation mode is now supported on both reads and writes.
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The block device major and minor numbers are determined from the
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tape's relative position in the ide interfaces, as explained in ide.c.
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The character device interface consists of the following devices:
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ht0 major 37, minor 0 first IDE tape, rewind on close.
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ht1 major 37, minor 1 second IDE tape, rewind on close.
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...
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nht0 major 37, minor 128 first IDE tape, no rewind on close.
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nht1 major 37, minor 129 second IDE tape, no rewind on close.
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...
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Run /dev/MAKEDEV to create the above entries.
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The general magnetic tape commands compatible interface, as defined by
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include/linux/mtio.h, is accessible through the character device.
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General ide driver configuration options, such as the interrupt-unmask
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flag, can be configured by issuing an ioctl to the block device interface,
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as any other ide device.
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Our own ide-tape ioctl's can be issued to either the block device or
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the character device interface.
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Maximal throughput with minimal bus load will usually be achieved in the
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following scenario:
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1. ide-tape is operating in the pipelined operation mode.
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2. No buffering is performed by the user backup program.
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================================================================================
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Some Terminology
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----------------
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IDE = Integrated Drive Electronics, meaning that each drive has a built-in
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controller, which is why an "IDE interface card" is not a "controller card".
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ATA = AT (the old IBM 286 computer) Attachment Interface, a draft American
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National Standard for connecting hard drives to PCs. This is the official
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name for "IDE".
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The latest standards define some enhancements, known as the ATA-6 spec,
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which grew out of vendor-specific "Enhanced IDE" (EIDE) implementations.
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ATAPI = ATA Packet Interface, a new protocol for controlling the drives,
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similar to SCSI protocols, created at the same time as the ATA2 standard.
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ATAPI is currently used for controlling CDROM, TAPE and FLOPPY (ZIP or
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LS120/240) devices, removable R/W cartridges, and for high capacity hard disk
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drives.
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mlord@pobox.com
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--
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Wed Apr 17 22:52:44 CEST 2002 edited by Marcin Dalecki, the current
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maintainer.
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Wed Aug 20 22:31:29 CEST 2003 updated ide boot options to current ide.c
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comments at 2.6.0-test4 time. Maciej Soltysiak <solt@dns.toxicfilms.tv>
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