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From: Olaf Hering <olh@suse.de>
To: linux-hotplug@vger.kernel.org
Subject: Re: [PATCH] avoid unaligned access to data
Date: Sat, 13 Mar 2004 00:03:38 +0000	[thread overview]
Message-ID: <20040313000338.GC29248@suse.de> (raw)
In-Reply-To: <20040229204531.GA25308@suse.de>

 On Fri, Mar 12, Greg KH wrote:

> On Sun, Feb 29, 2004 at 09:45:31PM +0100, Olaf Hering wrote:
> > 
> > the data access in udevinfo is usually unaligned, due to the fact that
> > the struct is at offset strlen(sysfspath). That makes an ia64 kernel
> > rather unhappy. Unless I miss something, this change makes it happy by
> > making an incompatible change to the database.
> > 
> > 
> > diff -p -purN udev-018/udevdb.c udev-018.align/udevdb.c
> > --- udev-018/udevdb.c	2004-02-19 19:38:36.000000000 +0100
> > +++ udev-018.align/udevdb.c	2004-02-22 13:05:15.000000000 +0100
> > @@ -44,6 +44,8 @@
> >  static TDB_CONTEXT *udevdb;
> >  
> >  
> > +#define	my_key_align (__alignof__(char *))
> 
> Hm, can't we just pad out our data structures to provide the proper
> alignment?  If it's really necessary...

its not the alignment of struct members, but the alignment of the
struct itself. we could copy the struct from the database to an aligned
area on the stack or malloc buffer. but thats not faster than the
unaligned access.

-- 
USB is for mice, FireWire is for men!

sUse lINUX ag, n√úRNBERG


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  parent reply	other threads:[~2004-03-13  0:03 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-02-29 20:45 [PATCH] avoid unaligned access to data Olaf Hering
2004-03-05 22:21 ` Olaf Hering
2004-03-12 23:40 ` Greg KH
2004-03-12 23:41 ` Greg KH
2004-03-12 23:59 ` Olaf Hering
2004-03-13  0:03 ` Olaf Hering [this message]
2004-03-13  0:11 ` Greg KH
2004-03-13  9:58 ` Olaf Hering
2004-03-13 16:57 ` Johannes Erdfelt

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