: Partition table display bogus...

Having partition table troubles here with 2.6.7 on hdc: unknown partition table. but not on hda.

Using 2.6.6 kernel, hdc is handled just fine, partitions are visible. The boot drive is hda, drive hdc is for other optional mount points.

VP_IDE: IDE controller at PCI slot 0000:00:07.1
VP_IDE: chipset revision 6
VP_IDE: not 100% native mode: will probe irqs later
VP_IDE: VIA vt82c686b (rev 40) IDE UDMA100 controller on pci0000:00:07.1

    ide0: BM-DMA at 0xd000-0xd007, BIOS settings: hda:DMA, hdb:pio
    ide1: BM-DMA at 0xd008-0xd00f, BIOS settings: hdc:DMA, hdd:pio

hda: WDC AC26400B, ATA DISK drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
hdc: QUANTUM FIREBALL CR8.4A, ATA DISK drive
ide1 at 0x170-0x177,0x376 on irq 15
ide2: I/O resource 0x3EE-0x3EE not free.
ide2: ports already in use, skipping probe
hda: max request size: 128KiB
hda: 12594960 sectors (6448 MB) w/512KiB Cache, CHS=13328/15/63
hda: hda1 hda2 hda3 < hda5 hda6 >
hdc: max request size: 128KiB
hdc: 16514064 sectors (8455 MB) w/418KiB Cache, CHS=16383/16/63
hdc: unknown partition table
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It's been said in this thread that the kernel no longer guesses a geometry; it's also been said elsewhere that the kernel doesn't use CHS at all. What do I put on the kernel parameter line to give a define geometry? I've tried hdc=lba32, with no success.

Well, I suppose whatever geometry you invent will make no difference at all. Roughly speaking, Linux does not use any geometry.

Also, the geometry change you refer to is old, not something that happened during 2.6.

Since reading the partition table is the very first thing that happens on the disk, any kind of IDE problem will cause problems reading the pt

Check whether you can read that disk using dd. Check that fdisk still can read the table on that disk. Go back to 2.6.6 and check that the pt table is still OK. Check what type it is, and that your 2.6.7 kernel still has configured that type.

Using
fdisk v2.11u

displays the partition table for the drive that the kernel claims has an unknown partition table. The bootable flag indicator is neither blank nor an *; instead it was the ? character. Toggling the bootable flag in fdisk (bringing up the * ) and writing the changed partition table allowed the booting kernel to then read
the partition table. This partition table has not been touched for many a kernel
version and has been identified by all the previous kernels, through 2.6.6. Would the change that stopped the kernel from "guessing" the disk geometry have brought out the sensitivity to whatever was not correct with the PT?

Quoting Andries Brouwer :

Ah, excellent. See - I have no memory.

No - I keep repeating: please stop this geometry nonsense.

This is something entirely different. Linux does automatic partition recognition. That of course is bad, especially if there is no partition table at all, like on certain ZIP drives and memory cards for digital cameras (that behave like big floppies). In order to guess right more often the kernel now only believes that something is a valid DOS-type partition table when there is a valid bootable flag indicator (0 or 0x080).
You had garbage there (or at least an unusual value) - and the garbage was harmless, but now causes the kernel to reject this table.

Remains the question: do you have any idea from where you got this unusual value?

Andries