Re: [PATCH] bsg, block layer sg

[Erik Andersen <andersen@codepoet.org>]

On Thu Mar 02, 2006 at 12:19:46PM +0100, Jens Axboe wrote:
> Hi,
> 
> After all that SG_IO and cdrecord talk, I decided to brush off the bsg
> driver I wrote some time ago. Basically this is a full (aims to be at
> least, probably still some minor bits missing) SG v3 interface. It
> supports both SG_IO (which we just pass through for now), as well as
> read/write and readv/writev of sg_io_hdr structures.

After this is merged I suppose I could then, i.e.  run an SG_IO
ioctl doing i.e.  INQUIRY_CMD with some random block device, such
as an /dev/nbd0, or /dev/loop0, or some such.  Which in general
does not seem to make any sense at all unless the block device
has some physical device level support for SCSI/ATAPI/MMC.  So
while it addresses the needs of cdrecord and friends for CD
burning, does it make sense to implement this as a general
capability for all block devices?  I'm not objecting or arguing,
I'm simply puzzled why a generic SG_IO layer for _all_ block
devices (whether SCSI/ATAPI/MMC capable or not) is useful?

 -Erik

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Erik B. Andersen             http://codepoet-consulting.com/
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