From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Akinobu Mita <akinobu.mita@gmail.com>
Cc: linux-scsi@vger.kernel.org, Don Brace <don.brace@pmcs.com>,
iss_storagedev@hp.com, storagedev@pmcs.com,
Adam Radford <linuxraid@lsi.com>,
Kashyap Desai <kashyap.desai@avagotech.com>,
Sumit Saxena <sumit.saxena@avagotech.com>,
Uday Lingala <uday.lingala@avagotech.com>,
megaraidlinux.pdl@avagotech.com
Subject: Re: [PATCH 0/7] scsi: Fix transfer length 0 for 6-byte r/w commands
Date: Sat, 16 May 2015 09:46:10 -0700 [thread overview]
Message-ID: <1431794770.2181.7.camel@HansenPartnership.com> (raw)
In-Reply-To: <1431760673-7180-1-git-send-email-akinobu.mita@gmail.com>
On Sat, 2015-05-16 at 16:17 +0900, Akinobu Mita wrote:
> For 6-byte r/w commands, transfer length 0 means 256 blocks of data,
> not 0 block.
>
> But some drivers consider transfer length 0 as 0 block.
> Fortunately, the scsi disk driver sets up 10-byte r/w commands for
> 256 blocks of data instead of 6-byte r/w commands. So this could be
> an issue when SCSI commands are issued by SG_IO ioctl.
6-byte commands are obsolete, so there's not a lot of point in doing
this; however, in the early days of SCSI, there was considerable
confusion about what 0 transfer length meant (I think it wasn't until
SCSI-2 that it was clarified). Even today, USB drive manufacturers have
considerable difficulty with it, that's why the sd driver avoids it, as
would any sensible program doing sg_io.
James
prev parent reply other threads:[~2015-05-16 16:46 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-16 7:17 [PATCH 0/7] scsi: Fix transfer length 0 for 6-byte r/w commands Akinobu Mita
2015-05-16 7:17 ` [PATCH 1/7] hpsa: fix " Akinobu Mita
2015-05-16 7:17 ` [PATCH 2/7] 3w-xxxx: " Akinobu Mita
2015-05-16 7:17 ` [PATCH 3/7] 3w-9xxx: " Akinobu Mita
2015-05-16 7:17 ` [PATCH 4/7] scsi: trace: " Akinobu Mita
2015-05-16 7:17 ` [PATCH 5/7] staging: rts5208: " Akinobu Mita
2015-05-16 7:17 ` [PATCH 6/7] megaraid_mbox: " Akinobu Mita
2015-05-16 7:17 ` [PATCH 7/7] megaraid: " Akinobu Mita
2015-05-16 16:46 ` James Bottomley [this message]
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