Re: MCS field: RFA

From: Johannes Berg <johannes-cdvu00un1VgdHxzADdlk8Q@public.gmane.org>
To: David Young <dyoung-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org>
Cc: radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org
Subject: Re: MCS field: RFA
Date: Thu, 25 Mar 2010 21:57:15 -0700	[thread overview]
Message-ID: <1269579436.4581.0.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <20100325235000.GX414-eZodSLrBbDpBDgjK7y7TUQ@public.gmane.org>

On Thu, 2010-03-25 at 18:50 -0500, David Young wrote:
> On Tue, Feb 02, 2010 at 01:54:25PM -0600, David Young wrote:
> > On Mon, Feb 01, 2010 at 10:09:37PM +0000, Bill Stafford wrote:
> > > I also have a question about how the RadioTap design deals with information
> > > that may not be available. I know that RadioTap works for many different
> > > drivers, and I am wondering if all the drivers get full information about
> > > the packets.
> > 
> > The problem of don't-know/don't-care flags has come up before.  It'd be
> > nice to have a general solution.
> 
> I've been thinking about this.  Instead of adding 2**n-byte aligned
> fields with don't-know/don't-care flags, what do people think about
> using the presence bits in the header to indicate the presence of
> 1-bit-wide fields?

Seems like a good idea, but I would suggest reserving a whole block of
them, or potentially an entire namespace, so we don't end up aligning
all the time?

johannes