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From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: Erez Zilber <erezz@Voltaire.COM>
Cc: linux-scsi@vger.kernel.org
Subject: Re: usage of max_sectors in scsi_host_template
Date: Tue, 06 Nov 2007 19:32:57 +0100	[thread overview]
Message-ID: <4730B359.8020806@s5r6.in-berlin.de> (raw)
In-Reply-To: <47304E70.9090005@Voltaire.COM>

Erez Zilber wrote:
> I'm not sure that I understand the meaning of max_sectors in 
> scsi_host_template.

Did you have a look at scsi_mid_low_api.txt?
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=Documentation/scsi/scsi_mid_low_api.txt;h=6f70f2b9327e1f0db7bc05bdbf2d6ce3b2fcbdcf#l1232

> Is it the maximum data length of a single SCSI command?

Yes.

> Is it in bytes?

No, it is in units of 512 bytes.

> What's the size of a sector?

"Usually" 512 bytes according to above doc.  Always 512 bytes from the
point of view of block/ll_rw_blk.c::blk_queue_max_sectors().
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=block/ll_rw_blk.c;h=75c98d58f4ddf7252e2717e0924b9d6a8925b4e5#l590
-- 
Stefan Richter
-=====-=-=== =-== --==-
http://arcgraph.de/sr/

  reply	other threads:[~2007-11-06 18:32 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-06 11:22 usage of max_sectors in scsi_host_template Erez Zilber
2007-11-06 18:32 ` Stefan Richter [this message]
2007-11-07 14:46   ` Erez Zilber
2007-11-07 18:53     ` Stefan Richter
2007-11-07 20:24     ` Mike Christie

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