Re: [CFT][PATCH] cleanup of partition code

From: Erik Andersen (andersen@codepoet.org)
Date: Mon Oct 01 2001 - 01:04:46 EST


On Mon Oct 01, 2001 at 01:27:54AM -0400, Alexander Viro wrote:
>
>
> On Sun, 30 Sep 2001, Erik Andersen wrote:
>
> > On Sun Sep 30, 2001 at 06:31:55PM -0400, Alexander Viro wrote:
> > >
> > > One thing that doesn't work yet is support of Acorn partitions -
> > > I'm switching it to pagecache right now.
> >
> > Well, acorn is broken anyways.... Try enabling in on a device
> > with native 2048 byte sectors and _no_ partition table will be
> > found on those devices (just an error msg resulting from acorn)
>
> Could you send me an example of such animal? I don't mean the disk itself -
> just the contents of relevant sectors (i.e. everything except the contents
> of partitions themselves).

Here is what I normally see (in this case with 2.4.9-ac17):

        scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.1
                <Adaptec 2940 Ultra SCSI adapter>
                aic7880: Ultra Single Channel A, SCSI Id=7, 16/255 SCBs

        (scsi0:A:4): 10.000MB/s transfers (10.000MHz, offset 15)
          Vendor: OLYMPUS Model: MOS364 Rev: 1.02
          Type: Optical Device ANSI SCSI revision: 02
        (scsi0:A:5): 10.000MB/s transfers (10.000MHz, offset 15)
          Vendor: OLYMPUS Model: MOS364 Rev: 1.02
          Type: Optical Device ANSI SCSI revision: 02
        [----------snip-------------]
        Attached scsi removable disk sda at scsi0, channel 0, id 4, lun 0
        Attached scsi removable disk sdb at scsi0, channel 0, id 5, lun 0
        SCSI device sda: 310352 2048-byte hdwr sectors (636 MB)
        sda: Write Protect is off
         sda: sda1
        SCSI device sdb: 310352 2048-byte hdwr sectors (636 MB)
        sdb: Write Protect is off
         sdb: sdb1

Everything looks fairly normal... I have 2 640Meg SCSI magneto optical drives
with a single partiton on the media in each (working as expected). Now lets
enable some stuff:

        +CONFIG_ACORN_PARTITION=y
        +CONFIG_ACORN_PARTITION_ICS=y
        +CONFIG_ACORN_PARTITION_ADFS=y
        +CONFIG_ACORN_PARTITION_POWERTEC=y
        +CONFIG_ACORN_PARTITION_RISCIX=y

Now I see:

        Attached scsi removable disk sda at scsi0, channel 0, id 4, lun 0
        Attached scsi removable disk sdb at scsi0, channel 0, id 5, lun 0
        SCSI device sda: 310352 2048-byte hdwr sectors (636 MB)
        sda: Write Protect is off
         sda:<5>ll_rw_block: device 08:00: only 2048-char blocks implemented (1024)
         unable to read boot sectors / partition sectors
        SCSI device sdb: 310352 2048-byte hdwr sectors (636 MB)
        sdb: Write Protect is off
         sdb:<5>ll_rw_block: device 08:10: only 2048-char blocks implemented (1024)
         unable to read boot sectors / partition sectors

Note the ll_rw_block msg from where the acorn stuff is not reading in units
of the physical sector size? Also notice the "unable to read..." msg, which
is where acorn chokes the partition table scanning...

So now, while fdisk is still able to see that partitions exist

        [andersen@dillweed andersen]$ fdisk -l /dev/sda
        Note: sector size is 2048 (not 512)

        Disk /dev/sda: 64 heads, 32 sectors, 151 cylinders
        Units = cylinders of 2048 * 2048 bytes

           Device Boot Start End Blocks Id System
        /dev/sda1 * 1 151 618432 83 Linux

the acorn stuff has caused the partition scan to abort prematurely, such that
proc partitions (and Linux) know nothing about the device's partitions. I can
give you a dd from one of these disks, but I doubt that would show the error...

 -Erik

--
Erik B. Andersen   email:  andersee@debian.org, formerly of Lineo
--This message was written using 73% post-consumer electrons--
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