From: Rogier Wolff <R.E.Wolff@BitWizard.nl>
To: bert hubert <ahu@ds9a.nl>,
Shesha Sreenivasamurthy <shesha@inostor.com>,
"'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>,
"'kernelnewbies@nl.linux.org'" <kernelnewbies@nl.linux.org>
Subject: Re: O_DIRECT
Date: Sat, 24 Jul 2004 11:56:29 +0200 [thread overview]
Message-ID: <20040724095629.GA9434@bitwizard.nl> (raw)
In-Reply-To: <20040720184824.GA30090@outpost.ds9a.nl>
On Tue, Jul 20, 2004 at 08:48:24PM +0200, bert hubert wrote:
> On Tue, Jul 20, 2004 at 10:27:57AM -0700, Shesha Sreenivasamurthy wrote:
> > I am having trouble with O_DIRECT. Trying to read or write from a block
> > device partition.
> >
> > 1. Can O_DIRECT be used on a plain block device partition say
> > "/dev/sda11" without having a filesystem on it.
>
> As fas as I know, yes, but be aware that O_DIRECT requires page aligned
> addresses! (an integral of 4096 on most systems).
Agreed, and I can tell you it works with raw disk devices. The code
we use is:
p = malloc (blocksize + PAGE_SIZE);
buf = (void *) (( ((long)p) + PAGE_SIZE -1 ) & ~(PAGE_SIZE-1));
Roger.
--
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2600998 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
**** "Linux is like a wigwam - no windows, no gates, apache inside!" ****
next prev parent reply other threads:[~2004-07-24 9:56 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-20 17:27 O_DIRECT Shesha Sreenivasamurthy
2004-07-20 18:48 ` O_DIRECT bert hubert
[not found] ` <40FD6FCB.5020408@inostor.com>
2004-07-20 20:17 ` O_DIRECT bert hubert
2004-07-21 0:10 ` O_DIRECT Rob van Nieuwkerk
2004-07-21 14:45 ` O_DIRECT Devel
[not found] ` <40FE9F3F.2090205@inostor.com>
2004-07-22 9:46 ` O_DIRECT Devel
2004-07-24 9:56 ` Rogier Wolff [this message]
2004-07-26 1:24 ` O_DIRECT Andrew Morton
2004-07-21 0:05 ` O_DIRECT Rob van Nieuwkerk
[not found] ` <40FEA382.8050700@inostor.com>
2004-07-21 17:20 ` O_DIRECT Rob van Nieuwkerk
[not found] ` <40FEAF70.4070407@inostor.com>
2004-07-21 18:15 ` O_DIRECT Rob van Nieuwkerk
2004-07-21 18:45 ` O_DIRECT Shesha Sreenivasamurthy
2004-07-21 23:18 ` O_DIRECT Shesha Sreenivasamurthy
2004-07-21 23:54 ` O_DIRECT Rob van Nieuwkerk
2004-07-22 0:00 ` O_DIRECT Shesha Sreenivasamurthy
2004-07-22 0:18 ` O_DIRECT Rob van Nieuwkerk
2004-07-22 0:48 ` O_DIRECT Shesha Sreenivasamurthy
-- strict thread matches above, loose matches on Subject: below --
2004-12-02 2:50 O_DIRECT Lever, Charles
2004-12-02 1:01 O_DIRECT Steve French
[not found] <200306262021.h5QKLhN10771@devserv.devel.redhat.com>
[not found] ` <1056706819.2418.11.camel@sisko.scot.redhat.com>
2003-06-27 10:35 ` O_DIRECT Stephen C. Tweedie
2003-06-27 11:07 ` O_DIRECT Alan Cox
[not found] <200208291113.g7TBDut26852@tench.street-vision.com>
2002-08-29 11:22 ` O_DIRECT Peter T. Breuer
2002-08-29 12:14 ` O_DIRECT Peter T. Breuer
2002-08-29 11:04 O_DIRECT Peter T. Breuer
2001-04-12 21:09 O_DIRECT Andrea Arcangeli
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