From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7AA09C77B7A for ; Thu, 18 May 2023 17:06:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229609AbjERRGd (ORCPT ); Thu, 18 May 2023 13:06:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229506AbjERRGc (ORCPT ); Thu, 18 May 2023 13:06:32 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F9AE121; Thu, 18 May 2023 10:06:32 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6AAFA64557; Thu, 18 May 2023 17:06:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2548DC433D2; Thu, 18 May 2023 17:06:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684429590; bh=XL8Q8LxpeG+xUSW+d2Fhz16+YABT67r3plx3O+Y35ag=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SYDwNwjeRfNEkfoyIRyJq3Fohsc3ZIt3WbvX+OQ++ceTWjibgZ24NbiSU4vfGEufv E7/MG8tjVbYn8mfTzAqH4bsSYhCAPy4wioXysSz9c9jyKzRIwkWR4YFCfxF+QkoWHa SjilsAYEF5gzcKD+jg9x90stMTD6SLJsxPxhPjJZW0StGE3IfSLuaGFwHOy8eBK4OM i59muo8WKsAEN4/0QTZOrGqA5Hx1JqDnrSJpknH+axhqo4xWAcFso0ezUz0FDXuSnL xP1/Z3FypEnI8MGE/wgMHsOmzfJ6SUoZ43dLzibDtQNclaBobAMq0a6Jey31YekcNb 7Uu1mISU27XeQ== Date: Thu, 18 May 2023 18:06:24 +0100 From: Conor Dooley To: Palmer Dabbelt Cc: Conor Dooley , anup@brainfault.org, ajones@ventanamicro.com, Paul Walmsley , robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, Alistair Francis , apatel@ventanamicro.com, atishp@atishpatra.org, jrtc27@jrtc27.com, rick@andestech.com, ycliang@andestech.com, linux-riscv@lists.infradead.org, qemu-riscv@nongnu.org, u-boot@lists.denx.de, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1] dt-bindings: riscv: deprecate riscv,isa Message-ID: <20230518-elective-mossy-1bf147f5e9b8@spud> References: <20230518-hammock-doornail-478e8ea8e6a7@wendy> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="TKxZvzqyNscVPD5H" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org --TKxZvzqyNscVPD5H Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 18, 2023 at 07:41:17AM -0700, Palmer Dabbelt wrote: > On Thu, 18 May 2023 07:06:17 PDT (-0700), Conor Dooley wrote: > > On Thu, May 18, 2023 at 07:13:15PM +0530, Anup Patel wrote: > > > On Thu, May 18, 2023 at 4:02=E2=80=AFPM Andrew Jones wrote: > > > > On Thu, May 18, 2023 at 09:58:30AM +0100, Conor Dooley wrote: > > > One downside of this new approach is it will increase the size of DTB. > > > Imaging 50 such DT properties in 46 CPU DT nodes. > >=20 > > I should do a comparison between 50 extensions in riscv,isa and doing > > this 50 times and see what the sizes are. >=20 > I'm not sure how sensitive people are to DT size (presumably it'd be DTB > size)? >=20 > It's also not clear what we can do about it: RISC-V has lots of extension= s, > that's going to take encoding space. Sticking with an ambiguous encoding > because it's smaller seems like a way to get burned in the long run. I did actually go an look at this. I cheated a little and renamed the properties to "riscv,isa-ext-foo", which is about as communicative IMO as the longer name I currently have, but may seem more agreeable to the size conscious. I added 30 cpu nodes to mpfs.dtsi, each with 100 extensions of 6 chars long. With just the string, containing "rv64imafdc_zabcde_...", it was unreadable, but "only" took up 46k. I then removed the multiletter extensions from riscv,isa & switched to riscv,isa-base & 100 booleans. IMO it was more readable (although still quite bad!), but took up 62k. Removing all of the boolean properties, leaving me with 30 addtional harts with "rv64imafdc" only, was 26k. I think the generic limit for dtb files is 2 MiB? To me the size increase doesn't sound like a bit problem. --TKxZvzqyNscVPD5H Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZGZbEAAKCRB4tDGHoIJi 0s2UAQC3dbtneTDqOvEpuMHz7vzTT/qCO/nEAhYVxRjH0MasoQD+IWeuh0pZj7Y/ NPtfbaq3ryBkiGdWFoAC2ls1S9xcNAo= =0mwD -----END PGP SIGNATURE----- --TKxZvzqyNscVPD5H--