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[89.176.104.3]) by mx.google.com with ESMTPSA id bw3sm1452761lbd.14.2014.08.25.13.40.39 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 25 Aug 2014 13:40:39 -0700 (PDT) From: Martin Jansa X-Google-Original-From: Martin Jansa Date: Mon, 25 Aug 2014 22:40:46 +0200 To: Khem Raj Message-ID: <20140825204046.GU20524@jama> References: <53F77370.2060603@balister.org> <20140822133349.76751634@e6410-2> <20140822193910.GD20524@jama> <20140822154954.04d4fc02@e6410-2> <20140822214626.GF20524@jama> <20140822170626.13280b11@e6410-2> <20140822222642.GG20524@jama> <53FB8A87.1010202@windriver.com> <20140825193523.GB23339@haswell> MIME-Version: 1.0 In-Reply-To: <20140825193523.GB23339@haswell> User-Agent: Mutt/1.5.23 (2014-03-12) Cc: openembedded-core@lists.openembedded.org Subject: Re: [PATCH 0/1] Change default for cortexa* to armv7at-neon. X-BeenThere: openembedded-core@lists.openembedded.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Patches and discussions about the oe-core layer List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 25 Aug 2014 20:40:45 -0000 X-Groupsio-MsgNum: 56924 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="huLXOlJ1ghGp/P5+" Content-Disposition: inline --huLXOlJ1ghGp/P5+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Aug 25, 2014 at 12:35:23PM -0700, Khem Raj wrote: > On 14-08-25 14:12:07, Mark Hatle wrote: > > On 8/22/14, 5:26 PM, Martin Jansa wrote: > > >On Fri, Aug 22, 2014 at 05:06:26PM -0500, Peter Seebach wrote: > > >>On Fri, 22 Aug 2014 23:46:26 +0200 > > >>Martin Jansa wrote: > > >> > > >>>changing > > >>>default DEFAULTTUNE (and TUNE_PKGARCH with that) to have thumb while > > >>>still building with -marm doesn't make much sense to me and is only > > >>>confusing. > > >> > > >>I think the distinction is that if you use armv7at-neon, you *can* bu= ild > > >>specific packages with thumb. Mostly, I guess, I don't think it makes= sense > > >>to use a tuning that specifically states that it can't run thumb code= for > > >>processors which can. Although... May not be an important distinction= , really, > > >>as you note. > > > > > >>I don't think it makes sense to use a tuning that specifically states > > >>that it can't run thumb code >=20 > yes. We should not have such case in armv7+=20 >=20 > >=20 > > The defaulttune is supposed to supply what the processor and ABI are ca= pable of. > >=20 > > So in the case of armv7a, it's saying no thumb support at all, this inc= luded > > thumb interwork. >=20 > if thats what we do then we are wrong. Since thumb interwork is > mandatory when we claim EABI compatibility and I think we have stopped > supporting Old ABI hence EABI is default which means interworking is > inherent. >=20 > >=20 > > armv7at says that the processor supports thumb, and interwork -should- = be > > enabled. (It can of course be manually disabled, but that's another is= sue > > to be dealt with...) >=20 > FWIW adding 't' in there should just be done when the resulting binary > is compiled using thumb ISA, using 't' to qualify interworking > capablility is not required. That's what http://patchwork.openembedded.org/patch/70985/ was trying to fix. Now we add t (or t2) for every DEFAULTTUNE which adds thumb to TUNE_FEATURES (for packages with both thumb and arm ISA). > > armv7at doesn't say it actually includes thumb combines binaries. (I a= rgued > > originally it should, but was overruled for a variety of reasons... not= the > > least of which is the interwork enabled, and multilib issues with 'same= abi' > > configurations.) > >=20 > > So I agree the default should be armv7at or armv7at-neon, unless there = is a > > compelling reason to leave it as a default with interwork disabled. >=20 > I dont believe thats the case we simply should not be able to disable > interworking. >=20 > >=20 > > As for the hard float question. I'm torn on this.. for compatibility a= lot > > of the industry is still soft-float based, and frankly I've not exactly > > encouraged it with my customers.. (I'm not seeing general performance > > improvements, only improvements in select artificial benchmarks, or spe= cific > > pieces of code.) > >=20 > > But if changing the default to hard float were generally agreed upon (f= or > > architectures where VFP are available) then I wouldn't object. > >=20 >=20 > I would leave that choice to distributions for now > --=20 > _______________________________________________ > Openembedded-core mailing list > Openembedded-core@lists.openembedded.org > http://lists.openembedded.org/mailman/listinfo/openembedded-core --=20 Martin 'JaMa' Jansa jabber: Martin.Jansa@gmail.com --huLXOlJ1ghGp/P5+ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEARECAAYFAlP7n04ACgkQN1Ujt2V2gBwR8QCfYihMiIY+9n64k7ToE8+buT0+ yvoAoKhi6uR5M4UVQi9bfOTH9xC21vr6 =hf29 -----END PGP SIGNATURE----- --huLXOlJ1ghGp/P5+--