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 E64B1C7EE22 for ; Mon, 8 May 2023 18:17:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229492AbjEHSRB (ORCPT ); Mon, 8 May 2023 14:17:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57256 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230187AbjEHSRA (ORCPT ); Mon, 8 May 2023 14:17:00 -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 0DF535BBE for ; Mon, 8 May 2023 11:17:00 -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 9715262135 for ; Mon, 8 May 2023 18:16:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6522DC433A0; Mon, 8 May 2023 18:16:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683569819; bh=05ZEnpDryaZ3pWwm2uM1BaK+nfW//+toX2uQFMeA9T4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HJGrfWGsDd1s7R5AE+0X9NTaSLnSiTl1CDjI2qlfcq8hhAqOCmAzMcydtEFIvBxYf kEQuQgx6k6zACnTIy2DQIAThvlziT4MzdAtavBoIJ+AoY6AMxPuJU2dXPxW+YKuNqX ZcWyVTekYnD9VAlWfQ/qEk0odrHvs1Z4RfkKOJ84kpsCTlZja+VwTzuSkmWSxSUY65 cAt7YdetUsJq7H6vdJPHzQtJoEEzngINLFx80lTw1eJvepAaziMwmcfh8NXI2fXban nScP2fYPcgIYUuIXBjKAceSEWgoe4x2zOVy7EpGAFoQeSPnkxqFwFQpSmiPXRRgqHR h0Yt4/U4EPHrg== From: Conor Dooley To: linux-riscv@lists.infradead.org Cc: conor@kernel.org, Conor Dooley , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Palmer Dabbelt , Paul Walmsley , Heiko Stuebner , Andrew Jones , Sunil V L , Yangyu Chen , devicetree@vger.kernel.org Subject: [RFC 1/6] dt-bindings: riscv: clarify what an unversioned extension means Date: Mon, 8 May 2023 19:16:21 +0100 Message-Id: <20230508-decibel-fender-532248c8f8ed@spud> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230508-hypnotic-phobia-99598439d828@spud> References: <20230508-hypnotic-phobia-99598439d828@spud> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1402; i=conor.dooley@microchip.com; h=from:subject:message-id; bh=pGmr6rcDfQk2g8LcKq7L3T1Gg5LY7Zpc7WjhfhPcmv8=; b=owGbwMvMwCFWscWwfUFT0iXG02pJDCmRNqXs1UuN814vn8Sa0ftPPlY/qv0kw/MDHrvlzNnmL fZ+EqTUUcrCIMbBICumyJJ4u69Fav0flx3OPW9h5rAygQxh4OIUgIkYqjAy9C6zY3LI67n333be fu4JGzQVn7mGCx7aetLUcHrggz8Z6gz/E/Ncdueu3ZM/WX156Ko9SwoPMs54b6hXwKaUckDT+Fw 3NwA= X-Developer-Key: i=conor.dooley@microchip.com; a=openpgp; fpr=F9ECA03CF54F12CD01F1655722E2C55B37CF380C Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org From: Conor Dooley C'est la vie, the spec folks reserve the ability to make incompatible changes between major versions of an extension. Their idea of backwards compatibility appears driven by the hardware perspective - it's backwards compatible if a later version is a subset of the existing extension. IOW, if you supported `x` in vN, you still support `x` in vN+1. However in software terms, code that was built for the vN's `x` extension may not work with the new definition. Signed-off-by: Conor Dooley --- Documentation/devicetree/bindings/riscv/cpus.yaml | 3 +++ 1 file changed, 3 insertions(+) diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml index db5253a2a74a..405915b04d69 100644 --- a/Documentation/devicetree/bindings/riscv/cpus.yaml +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml @@ -91,6 +91,9 @@ properties: Notably, riscv,isa was defined prior to the creation of the Zicsr and Zifencei extensions and thus "i" implies "zicsr_zifencei". + For the sake of backwards compatibility, an unversioned + extension means that the hart/platform is capable of + supporting version 1.0.0 of the extension. While the isa strings in ISA specification are case insensitive, letters in the riscv,isa string must be all -- 2.39.2