From: Jens Axboe <axboe@suse.de>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] 2.5 ide 48-bit usage
Date: Wed, 7 May 2003 18:46:13 +0200 [thread overview]
Message-ID: <20030507164613.GN823@suse.de> (raw)
In-Reply-To: <Pine.LNX.4.44.0305070915470.2726-100000@home.transmeta.com>
On Wed, May 07 2003, Linus Torvalds wrote:
>
> On Wed, 7 May 2003, Jens Axboe wrote:
> >
> > I did a patch for 2.4 some weeks ago that added (what I consider) proper
> > 48-bit lba usage to ide-disk.
>
> Ok, let me disagree a bit.
>
> At least if I read the patch correctly, theer's no way for upper layers to
> say "I want 48-bit addressing" - it's just turned on automatically for
> high sectors (or big transfers).
Correct.
> Well, you can mark the drive itself as wanting 48-bit transfers, but
> you can't do it on a per-request basis.
>
> And I think this is 100% equivalent to the 6 vs 10 vs 16-byte SCSI
> command issue, and I really think it should b esolved the same way.
> Namely, you should be able to (on a "struct request" level) explicitly
> say that you want the big requests, and then the default prep_fn()
> would do roughly what you do now by default.
I dunno what the purpose of that would be exactly, I guess to cater to
some hardware odditites?
> That way something like a SG_IO interface could force one mode or the
> other on a per-request basis.
Doesn't make a lot of sense in this case I think, because the command
associated with the SG_IO request would implicitly be either a 28-bit or
48-bit command based on the opcode of the request.
> Comments?
You haven't really convinced me yet. Is there some hardware out there
that requires to be addressed in 48-bit mode? If that is the case, then
yes a bit is missing to fully support that. We'd probably have a forced
addressing flag in the hwif, and the drive->addressing would inherit
that. So instead of
const int lba48 = rq_lba48(rq);
it would be
const int lba48 = rq_lba48(rq) || drive->addressing == FORCED_48;
(forgive the ugliness of the above construct, it's just meant to below
operation of it, rq_lba48 would probably just take both drive and rq as
parameter).
--
Jens Axboe
next prev parent reply other threads:[~2003-05-07 16:33 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-07 8:49 [PATCH] 2.5 ide 48-bit usage Jens Axboe
2003-05-07 16:28 ` Linus Torvalds
2003-05-07 16:46 ` Jens Axboe [this message]
2003-05-07 17:15 ` Linus Torvalds
2003-05-07 17:33 ` Jens Axboe
2003-05-07 17:42 ` Linus Torvalds
2003-05-07 17:50 ` Jens Axboe
2003-05-07 19:58 ` Bartlomiej Zolnierkiewicz
2003-05-07 20:19 ` Jens Axboe
2003-05-08 7:56 ` Jens Axboe
2003-05-08 11:01 ` Alan Cox
2003-05-08 12:01 ` Jens Axboe
2003-05-12 21:41 ` Mike Fedyk
2003-05-13 6:44 ` Jens Axboe
2003-05-08 11:34 ` Bartlomiej Zolnierkiewicz
2003-05-08 11:59 ` Jens Axboe
2003-05-08 12:20 ` Bartlomiej Zolnierkiewicz
2003-05-08 12:26 ` Jens Axboe
2003-05-08 12:36 ` Jens Axboe
2003-05-08 13:16 ` Bartlomiej Zolnierkiewicz
2003-05-08 13:23 ` Jens Axboe
2003-05-08 13:35 ` Bartlomiej Zolnierkiewicz
2003-05-08 13:37 ` Jens Axboe
2003-05-08 14:47 ` Jens Axboe
2003-05-08 14:51 ` Jens Axboe
2003-05-08 14:46 ` Alan Cox
2003-05-08 15:49 ` Bartlomiej Zolnierkiewicz
2003-05-08 16:16 ` Jens Axboe
2003-05-08 16:27 ` Linus Torvalds
2003-05-08 16:34 ` Jens Axboe
2003-05-08 16:59 ` Bartlomiej Zolnierkiewicz
2003-05-09 7:40 ` Jens Axboe
2003-05-08 22:06 ` Alan Cox
2003-05-09 7:06 ` Jens Axboe
2003-05-09 8:28 ` [PATCH][RFC] Sanitize hwif/drive addressing (was Re: [PATCH] 2.5 ide 48-bit usage) Jens Axboe
2003-05-09 11:07 ` Bartlomiej Zolnierkiewicz
2003-05-09 12:03 ` Jens Axboe
2003-05-07 21:45 ` [PATCH] 2.5 ide 48-bit usage Henning P. Schmiedehausen
2003-05-07 22:03 ` Alan Cox
2003-05-07 22:55 ` H. Peter Anvin
2003-05-07 18:29 ` Alan Cox
2003-05-07 19:30 ` Jens Axboe
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