LWN: Comments on "A simple block driver"

A simple block driver

metadaddy — Tue, 04 May 2010 16:08:28 +0000

I just ported the simple block driver to 2.6.31 - see A Simple Block Driver for Linux Kernel 2.6.31

-ENOTTY ?

strcmp — Mon, 25 Aug 2008 13:07:39 +0000

because it's the documented behaviour we have to implement here. the man page ioctl(2) says:

ENOTTY The specified request does not apply to the kind of object  that
       the descriptor d references.

sdb_init() - Queue removal on error

bigguiness — Tue, 06 Nov 2007 16:54:01 +0000

Just a minor comment/question.

In the sbd_init() function, if the register_blkdev() call fails shouldn't the Queue be removed
(blk_cleanup_queue(Queue);) before the function exits?

insmod sbd.ko error ??

rbartlett — Sat, 03 Nov 2007 00:39:22 +0000

The "sbd0: unknown partition table" is normal.  The allocated memory is uninitialized when the
module is first loaded so it can't contain a valid partition table.  You can either use sfdisk
or mkfs to create a partition table or file system in the allocated memory.  If mkfs is used,
the driver may subsequently be mounted.

I had to make a few minor changes to the driver to get it to this point.  I had to add the
following line to the sbd_ops structure:
".getgeo = sbd_blk_getgeo"
Then I had to create a function sbd_blk_getgeo with the code from the HDIO_GETGEO case from
the sbd_ioctl function.  This was because sfdisk complained that "Disk /dev/sbd0: cannot get
geometry".

The last thing I had to do was change "geo.start = 4" to geo.start = 0".  This was because
sfdisk complained that "Warning: start=4 - this looks like a partition rather than the entire
disk. Using fdisk on it is probably meaningless."

Once these changes were made, I was able to use sfdisk and mkfs on the device and mount it as
well.

insmod sbd.ko error ??

midhun001 — Mon, 13 Aug 2007 08:48:09 +0000

Hi All,

Even I got the same error. Please share it with me if you tion for this.

-Midhun

insmod sbd.ko error ??

sahib — Tue, 23 May 2006 06:01:06 +0000

HI
ITS ALI, I ALSO ENCOUNTERED THE SAME ERROR WHILE LOADING THAT SIMPLE BLOCK DEVICE DRIVER THAT SHOWS MSG LIKE "sbd0: unknown partition table" yet i came to know that it is due to the (add_disk)function call in the init function add_disk is necessary as it provide a block disk for block I/O's. now i am trying to solve it further if u have solved it! let me know coz i am also trying to learn this.
ALI(SAHIB)

insmod sbd.ko error ??

gg940231 — Wed, 19 Apr 2006 08:33:11 +0000

I make ok sbd.c <http://lwn.net/Articles/58720/>
linux 2.6.9
but some error:

> insmod sbd.ko
devfs_mk_dir: invalid argument.<6> sbd0: unknown partition table

-ENOTTY ?

xav — Thu, 15 Jan 2004 22:54:38 +0000

I don't understand the -ENOTTY in the sbd_ioctl(). Why not simply a -EINVAL ?