From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <46F80F45.7050406@domain.hid> Date: Mon, 24 Sep 2007 21:25:57 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <899865CA54E4444DAF2E3639C04C5F4805ED13@domain.hid> <46F7F868.2050904@domain.hid> <18168.1587.763871.556961@domain.hid> In-Reply-To: <18168.1587.763871.556961@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigEBBAED9F16BD91EBCE00C68E" Sender: jan.kiszka@domain.hid Subject: Re: [Xenomai-core] [RFC] Fast Context Switch Extension for ARM Linux List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gilles Chanteperdrix Cc: xenomai-core This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigEBBAED9F16BD91EBCE00C68E Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Gilles Chanteperdrix wrote: > Jan Kiszka wrote: > > Richard Cochran wrote: > > > I know that this is a bit off topic, yet perhaps some on this list= > > > have interest or knowledge in this area. I am also posting this id= ea > > > to the linux-arm-kernel list. > > >=20 > > > I would like to implement the ARM FCSE under Linux, using the Inte= l > > > IXP425 board. Before I start, I would like to ask: > > >=20 > > > 1. Has any work already been done in this area? > > >=20 > > > 2. Is there something about the current Linux MM that would make t= his > > > impractical? > >=20 > > Nothing is impossible (specifically as FASS proves its feasibility),= > > it's just a question how much work it is to implement it AND maintai= n it > > or merge it into standard Linux. And I cannot imagine ARM or its > > licensees dropping this feature without an acceptable alternative on= ce > > Linux started to use it broadly... >=20 > The feature was already dropped, it is deprecated in ARMv6. >=20 I'm not claiming to be an ARM insider, but browsing through some manuals makes me think that "The c13, Context ID Register, [...] replaces the FCSE PID register. Use of the FCSE PID Register is deprecated." Moreover: "The ARM1136JF-S processor implements the Fast Context Switch Extension (FCSE) and high vectors extension that are required to run Microsoft WindowsCE." Given this popular user, it is highly unlikely that a feature comparable to FCSE is going to be removed from the ARM architecture - at least as long as its cache is located at such an unpleasant place. Jan --------------enigEBBAED9F16BD91EBCE00C68E Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFG+A9HniDOoMHTA+kRAhXEAJ9tTpOgfKY68bx23rfy3REnBmlbDQCfQHOP qoqWqJih78bJbfHHFX6G9cU= =UA5E -----END PGP SIGNATURE----- --------------enigEBBAED9F16BD91EBCE00C68E--