From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mark Lord <mlord@pobox.com>
Date: Wed, 21 Apr 2010 14:13:45 +0000
Subject: Re: System hangs when using USB 3.0 HD with on Ubuntu
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 <4BCF0310.4000906@pobox.com> <1271858694.2893.47.camel@mulgrave.site>
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To: James Bottomley <James.Bottomley@suse.de>
Cc: ltuikov@yahoo.com, Alan Stern <stern@rowland.harvard.edu>, Sarah Sharp <sarah.a.sharp@linux.intel.com>, Jonas Schwertfeger <jschwertfeger@gmail.com>, Dinh.Nguyen@freescale.com, Sergei Shtylyov <sshtylyov@mvista.com>, Kay Sievers <kay.sievers@vrfy.org>, David Zeuthen <david@fubar.dk>, linux-hotplug@vger.kernel.org, linux-usb@vger.kernel.org, USB Storage List <usb-storage@lists.one-eyed-alien.net>, Matthew Dharm <mdharm-usb@one-eyed-alien.net>, linux-scsi@vger.kernel.org, Lennart Poettering <lennart@poettering.net>, Douglas Gilbert <dgilbert@interlog.com>

On 21/04/10 10:04 AM, James Bottomley wrote:
..
> But this isn't a userspace problem.  By the time we present the device
> to userspace, we already know what it is ... so you can go by device
> type and only use ATA_12 for disk devices.
..

And most tools / programs can indeed do that.

But hdparm's mission is to ignore what the kernel thinks,
and speak directly to the drive whenever possible.

Because hdparm is an important part of how we verify
that the kernel is correct (or not).  So I very much
prefer that it continue to work out the details as much
as it can without asking a possibly buggy kernel for help.

:)

That said.. what would you recommend as a way for a userspace
program to figure out whether to use ATA_12 or ATA_16 to talk
to a given arbitrary device name ?

I guess the info is in sysfs somewhere.

Thanks
-- 
Mark Lord
Real-Time Remedies Inc.
mlord@pobox.com