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From: Andries Brouwer <aebr@win.tue.nl>
To: Jens Axboe <axboe@suse.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
	Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH] only use 48-bit lba when necessary
Date: Fri, 4 Apr 2003 16:40:44 +0200	[thread overview]
Message-ID: <20030404144044.GA14371@win.tue.nl> (raw)
In-Reply-To: <20030404122936.GB786@suse.de>

On Fri, Apr 04, 2003 at 02:29:36PM +0200, Jens Axboe wrote:

> 48-bit lba has a non-significant overhead (twice the outb's, 12 instead

s/non-// ?

> of 6 per command), so it makes sense to use 28-bit lba commands whenever
> we can.
> 

> +	if (drive->addressing == 1 && block > 0xfffffff)
> +		lba48 = 1;

Hmm. I wonder whether we should be more cautious, and ask for lba48
as soon as some part of the interval is past this limit.
(say, block+nsectors > 0xfffffff)

I don't know whether the standard spells out what happens
at the boundary, but for example the LBA low/mid/high, DEV is required
to contain the sector number at the place the error occurred,
and that is possible only if one stays below the 28-byte sector limit.

Andries


  parent reply	other threads:[~2003-04-04 14:48 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-04-04 12:29 [PATCH] only use 48-bit lba when necessary Jens Axboe
2003-04-04 13:19 ` Juan Quintela
2003-04-04 13:22   ` Jens Axboe
2003-04-04 15:48     ` Juan Quintela
2003-04-04 15:54       ` Jens Axboe
2003-04-04 17:06         ` John Bradford
2003-04-04 14:40 ` Andries Brouwer [this message]
2003-04-04 15:13   ` Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2003-04-04 17:02 Chuck Ebbert
2003-04-17 14:20 ` Matt Mackall
2003-04-17 15:24   ` Timothy Miller
2003-04-17 16:05     ` Matt Mackall
2003-04-17 18:49       ` Timothy Miller
2003-04-18  1:34 Chuck Ebbert
2003-04-18  4:18 ` Matt Mackall
2003-04-18 14:34 ` Timothy Miller
2003-04-18  3:32 linux-kernel
2003-04-18  9:50 Chuck Ebbert

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