[plug] IDE-TAPE

[Craig Ringer]

> Nada, niente, nichts, nothing. From dmesg:
> 
>         ide0: BM-DMA at 0xffa0-0xffa7, BIOS settings: hda:DMA, hdb:DMA
>         hda: MAXTOR 6L040J2, ATA DISK drive
>         hdb: ST380011A, ATA DISK drive
>         blk: queue f88276c0, I/O limit 4095Mb (mask 0xffffffff)
>         blk: queue f88277fc, I/O limit 4095Mb (mask 0xffffffff)
>         ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
>         Journalled Block Device driver loaded
>         hda: attached ide-disk driver.
>         hda: host protected area => 1
>         hda: 78177792 sectors (40027 MB) w/1819KiB Cache,
>         CHS=77557/16/63, UDMA(33)
>         hdb: attached ide-disk driver.
>         hdb: host protected area => 1
>         hdb: 156301488 sectors (80026 MB) w/2048KiB Cache,
>         CHS=9729/255/63, UDMA(33)
>         Partition check:
>          /dev/ide/host0/bus0/target0/lun0: p1 p2 p3 p4 < p5 p6 p7 >
>          /dev/ide/host0/bus0/target1/lun0: unknown partition table

To me, that looks like the second ATA controller is disabled in BIOS or 
something.

> I did - as far as I recall, but I still am of the mind that if it's not
> happening in dmesg, it's not happening at all... As I understand it, in
> order of detection, BIOS => dmesg => /proc => /modules => working

Generally, you're quite right. If, however, you've defined an ATA device 
as ide-scsi, it may not be listed fully until support for it is loaded. 
Similarly, until a SCSI controller driver is loaded, nothing will show 
up about it or attached devices.

> This did spark another investigation. I looked at /proc/interrupts which
> reports:
> 
>                    CPU0       
>           0:    1353560          XT-PIC  timer
>           1:          2          XT-PIC  keyboard
>           2:          0          XT-PIC  cascade
>           8:          3          XT-PIC  rtc
>          10:       1599          XT-PIC  eth0
>          14:       6138          XT-PIC  ide0
>         NMI:          0 
>         LOC:    1353513 
>         ERR:          0
>         MIS:          0

Yeah, the controller isn't detecting or initializing properly, or 
something similar. Does it show up correctly in the output of 'lspci' or 
in /proc/pci ?

>>My understanding was linux accesses ide devices directly (hdds) without
>>using the bios ? Is this the same for cd drives and tape drives? My
>>experience is that if I have a hard disk disabled in the bios, linux will
>>still find it.
> 
> That is my understanding also.

It'll find it, but the disk may not work - I've seen it hang on boot, 
too. Linux usually won't find PCI devices disabled in BIOS, such as 
onboard sound or IDE controllers, and usually won't find serial or 
parallel ports disabled in BIOS either.

My next guess here would be the disk contoller accidentally disabled in 
BIOS. Alternately, perhaps the drive is somehow causing the controller 
to fail to init - I've never seen it (usually the kernel hangs on boot 
if it can't probe IDE devices that appear to be there) but I guess it 
could happen.

Craig Ringer