From: Jens Axboe <axboe@suse.de>
To: Douglas Gilbert <dougg@torque.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: cdrecord hangs my computer
Date: Thu, 11 Dec 2003 13:56:08 +0100 [thread overview]
Message-ID: <20031211125608.GG7599@suse.de> (raw)
In-Reply-To: <3FD444DD.4080206@torque.net>
On Mon, Dec 08 2003, Douglas Gilbert wrote:
> Yes dev=/dev/scd0 should work for "real" SCSI (and USB, IEEE1394
> and sATA [via libata] attached) cd/dvd players in lk 2.6.
> Copying the SG_IO ioctl and friends into the block
> layer isn't exactly pretty in lk 2.6. No doubt I'll be hearing from
> the author of cdrecord about some of the rough edges. Basically
> cdrecord is tricked into believing it is talking to an sg device.
It's not tricked, cdrecord should not care about device type. All it
needs to care about is SG_IO working or not.
> One rough edge is cdrecord's use of the SCSI_IOCTL_GET_IDLUN ioctl
> which encodes bus/channel/target/lun into an integer. cdrecord
> uses this for its dev=<n,m,q> notation. The drivers/block/scsi_ioctl.c
> implementation returns 0 in all cases. So if you have 2 or more
> ATAPI cd/dvd burners cdrecord's dev=<n,m,q> usage won't be able
> to differentiate.
Not sure I see any merrit in supporting that at all, but if so it would
be pretty easy to fake these.
> ide-scsi has always had problems (I spent about a week on it
> and gave up with only a few minor fixes to report) but it
> may be a useful "insurance" driver to keep around in lk 2.6 .
> [It is also needed for ATAPI tapes so its deprecatation
> warning might like to take into account the peripheral device
> type.]
It does, the 2.6 warning printed is just for CDROM devices.
> Well making the scsi layer handle some of the the most
> sophisticated storage devices and some of the most brain
> damaged at the same time is proving quite a challenge.
> With libata (and later SAS) sATA disks will be getting to
> the application space via the sd driver. And how will
> object storage devices fit into Linux's block-centric I/O
> architecture?
What makes you say that Linux has a block-centric IO architecture? 2.6
block io layer is quite happy to do byte-granularity SCSI commands for
you.
--
Jens Axboe
next prev parent reply other threads:[~2003-12-11 12:56 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-08 9:31 cdrecord hangs my computer Douglas Gilbert
2003-12-11 12:56 ` Jens Axboe [this message]
2003-12-11 16:15 ` Linus Torvalds
-- strict thread matches above, loose matches on Subject: below --
2003-12-15 13:29 Paul Marinceu
2003-12-06 19:08 Tero Knuutila
2003-12-06 18:27 Tero Knuutila
2003-12-06 12:39 Tero Knuutila
2003-12-06 8:01 Tero Knuutila
2003-12-06 8:12 ` Linus Torvalds
2003-12-06 8:54 ` Ethan Weinstein
2003-12-06 11:59 ` Måns Rullgård
2003-12-06 13:40 ` Wakko Warner
2003-12-06 14:37 ` John Bradford
2003-12-06 21:57 ` Linus Torvalds
2003-12-06 22:02 ` Larry McVoy
2003-12-06 22:32 ` Linus Torvalds
2003-12-07 11:01 ` Eduard Bloch
2003-12-07 16:18 ` Linus Torvalds
2003-12-08 16:21 ` bill davidsen
2003-12-08 17:46 ` Linus Torvalds
2003-12-09 12:38 ` Bill Davidsen
2003-12-08 17:53 ` Valdis.Kletnieks
2003-12-08 18:53 ` Linus Torvalds
2003-12-08 19:40 ` Valdis.Kletnieks
2003-12-09 14:50 ` Ian Soboroff
2003-12-09 20:42 ` Mikael Pettersson
2003-12-08 16:24 ` Martin J. Bligh
2003-12-08 4:36 ` Bob
2003-12-08 4:51 ` Larry McVoy
2003-12-07 0:16 ` Wakko Warner
2003-12-07 3:31 ` William Lee Irwin III
2003-12-07 4:49 ` Linus Torvalds
2003-12-08 16:13 ` bill davidsen
2003-12-08 17:38 ` Linus Torvalds
2003-12-06 16:42 ` Linus Torvalds
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