Subject: Re: [PATCH 2/2] mac80211: make rx radiotap header more flexible
From: Johannes Berg <johannes@sipsolutions.net>
To: bruno randolf <bruno@thinktube.com>
Cc: ath5k-devel@lists.ath5k.org, mcgrof@gmail.com, jirislaby@gmail.com,
	mickflemm@gmail.com, linux-wireless@vger.kernel.org,
	linville@tuxdriver.com, flamingice@sourmilk.net, jbenc@suse.cz
In-Reply-To: <200804292010.21367.bruno@thinktube.com>
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	 <20080407042549.9026.81997.stgit@localhost>
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	 <200804292010.21367.bruno@thinktube.com>
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Date: Wed, 30 Apr 2008 16:12:52 +0200
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> > Radiotap explicitly allows you to have a longer length than you need so
> > maybe we should just make sure to align things?
>=20
> are you talking about the alignment of the radiotap header itself? no, i =
just=20
> took care about the alignment requirements of the radiotap fields, relati=
ve=20
> to the start of radiotap. but it would be easy to add some additional len=
gth=20
> in ieee80211_rx_radiotap_len() and just leave that empty at the end.
>=20
> i think i don't understand all alignment requirements though...

Well all those stores there are usual 32/16-bit stores which will fault
on some architectures. See Documentation/unaligned-access.txt. Adding
some padding to make the radiotap header start at a mod8 boundary would
help.

johannes

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