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Title: Using offboard IDE controllers

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Using offboard IDE controllers

Applies to

SuSE Linux: Version 6.3

Symptom:

Your only hard drives in your system are coming up as hde, hdf, etc. Alternatively, possibly your CDROM and slower IDE drives are coming up as hda, hdb, but your fast DMA-66/DMA-33 drives are coming up as hde, hdf, and so forth.

Cause:

You most likely have an add-in PCI IDE controller. Even if you have never added any cards to your machine, this is quite possible. Notably some Gateway 2000 models shipped with Promise Ultra-66 controllers for some time. This is a common practice during the window of time between when add-in cards become available and when motherboards become widely available with the feature.

What happens is this, the Linux kernel scans for the existence of devices, and identifies your on-board IDE controller, and assumes this should be the "first" one. It (reasonably) sets it up as ide0 and ide1 (modern ide controllers have two channels) which respectively drive hda/b and hdc/d. It then locates the off-board controller and assigns it the name of ide2 and ide3. If your primary boot devices are attached to these controllers, they will be named from hde through hdh.

This is likely to be inconvenient for reasons which are beyond the scope of this discussion. If you are already using your system with your drives set up as thes higher drive letters and have not encountered difficulty, then do not feel a need to change anything. However, if this is during an install, you should probably follow the instructions below.

Solution:

  1. Write the floppy disk image disks/eide stored on CD number 1 to a floppy disk in accordance with the instructions in the manual. If you are already running linux, the simplest method is to place a umounted floppy disk in the drive, and simply enter a command such as:
        cp /cdrom/disks/eide /dev/fd0
        
    Please note the contents of the flopy disk will be erased.

  2. Boot from this floppy disk in order to perform the install.

  3. When you see the boot: prompt, please enter the following:
        boot: linux pci=reverse
        
    This should cause devices attached to the offboard controller to swap to hda - hdd, and any onboard device to move to hde - hdh.

  4. Complete the install as normal.

  5. At the LILO configuration screen, please add the folowing the the "Append line for hardware parameter": pci=reverse

    Special exeption

    On certain motherboards, it is possible for this to happen in the opposite manner. That is, on some boards, the offboard ide controller may appear as ide0/1 and the onboard as ide2/3. This is known to occur on certain ASUS boards with the CMD646 Revision 0 controller. (Please note this does not reflect any lack of quality in any other products made by either of these companies.) In this case, the pci=reverse functionality should still operate, but the effect of the flag will be the opposite of normal motherboard / controller combinations. Namely, with these boards, the offboard IDE controller will be 0/1, and if enabled, it will become 2/3.

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    Keywords: IDE CONTROLLER, ULTRA 66, PCI CONTROLLER, PCI IDE

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    Categories: IDE

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    SDB-jrodman_offboard_ide, Copyright SuSE GmbH, Nuremberg, Germany - Version: 14. Dec 1999
    SuSE GmbH - Last generated: 02. Jan 2000 01:37:25 by jrodman with sdb_gen 1.00.0