From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id 0849D138334 for ; Thu, 30 May 2019 13:15:52 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id A2BAEE089A; Thu, 30 May 2019 13:15:48 +0000 (UTC) Received: from smtp.gentoo.org (smtp.gentoo.org [IPv6:2001:470:ea4a:1:5054:ff:fec7:86e4]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 4B96AE0855 for ; Thu, 30 May 2019 13:15:48 +0000 (UTC) Received: from localhost (85-171-63-107.rev.numericable.fr [85.171.63.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: aballier) by smtp.gentoo.org (Postfix) with ESMTPSA id DD98734535C; Thu, 30 May 2019 13:15:45 +0000 (UTC) Date: Thu, 30 May 2019 15:15:38 +0200 From: Alexis Ballier To: Palmer Dabbelt Cc: mgorny@gentoo.org, gentoo-dev@lists.gentoo.org Subject: Re: [gentoo-dev] Announcing RISC-V Message-ID: <20190530151538.35300cd3@gentoo.org> In-Reply-To: References: <20190520114418.04551eb5@gentoo.org> Organization: Gentoo X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-dev@lists.gentoo.org Reply-to: gentoo-dev@lists.gentoo.org X-Auto-Response-Suppress: DR, RN, NRN, OOF, AutoReply MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Archives-Salt: bc67c46c-3d39-4349-889b-0e9adbf965e6 X-Archives-Hash: c0bb920c6511574e7ce81e3efc8c7808 On Wed, 29 May 2019 10:27:34 -0700 (PDT) Palmer Dabbelt wrote: > On Mon, 20 May 2019 02:44:18 PDT (-0700), aballier@gentoo.org wrote: > > On Sat, 18 May 2019 20:47:28 +0200 > > Micha=C5=82 G=C3=B3rny wrote: > > > >> On Fri, 2019-05-03 at 23:34 +0200, Andreas K. Huettel wrote: > >> > * We will initially add two profiles to profile.desc:=20 > >> > default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit > >> > hardfloat) default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64, > >> > i.e. hard/softfloat) > >>=20 > >> I still don't understand the purpose of this multilib. If you have > >> a hardfloat CPU, why would you ever build some of the software > >> softfloat? > > > > One reason I could imagine is that the hardfloat isn't IEEE 754 > > compliant. Searching through the RISC-V spec, it does not seem to be > > the case here (ie: it is required to be compliant) so I'm also > > wondering what is the point here. >=20 > The RISC-V floating-point extensions are IEEE-754 compliant, but > they're optional. We have chips without floating-point units, but > right now all the Linux capable chips have FPUs. As far as I know > there are no Linux binaries that anyone cares about that are compiled > for systems without hardware floating-point units, but I may be wrong > about that one. It was my understanding that FPU is not optional for rv64gc, is that correct ? > The non-FPU systems are much more interesting in embedded land, where > lots of users don't have FPUs. That's less relevant for Gentoo, but > I do use crossdev embedded toolchains. You'll probably not be using multilib here but rather a specific CHOST and/or flags to enable softfloat everywhere. [...] Alexis.