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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7FF5FECDE44 for ; Mon, 5 Nov 2018 09:09:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3D7C020862 for ; Mon, 5 Nov 2018 09:09:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ZJ7zAvdp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3D7C020862 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726876AbeKES1l (ORCPT ); Mon, 5 Nov 2018 13:27:41 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:53528 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726125AbeKES1l (ORCPT ); Mon, 5 Nov 2018 13:27:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=l3y/CO+0xDtVPVTAZdr/0+Ai079D0gY/8QOevfiqFiw=; b=ZJ7zAvdpt6se/Q//+yR+VF1EVO o+6hS32l4lBXiXa6YaTte9wSj5Qirtpho4hpmJvANl2rh8LLxQjQ7JyIy91GG9C8BLlmuHKqmlJO4 5GN3uHjnYJ5WzdnCvPhWXvqCM5WLCbxjCE+qAnDXZDoqVouY8RxZcAvfbZUppN8bvfX8Zox7p6htE Y0L/yJiCWU46DBohoEO1RC8RBaavCw5Nh9ZtByqAhzhgKAsmdnt2LAyB9vm8N8OboRzCHQXfp0Mh5 v0L6mwkn6rS4Dey5J2frCPlLyyiPY9HgvtRbE93gmkd4ooG/33ya4izZeOgHwyhfruzJIwCIeOWqU WDSA/qDQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gJasO-0004CY-CL; Mon, 05 Nov 2018 09:08:52 +0000 Date: Mon, 5 Nov 2018 01:08:52 -0800 From: Christoph Hellwig To: Arnd Bergmann Cc: Christoph Hellwig , Vincent Chen , aou@eecs.berkeley.edu, alankao@andestech.com, greentime@andestech.com, palmer@sifive.com, linux-kernel@vger.kernel.org, zong@andestech.com, kito@andestech.com, linux-riscv@lists.infradead.org, deanbo422@gmail.com Subject: Re: [RFC 0/2] RISC-V: A proposal to add vendor-specific code Message-ID: <20181105090852.GA14924@infradead.org> References: <20181101174857.du2zu4vnrhpu5asf@excalibur.cnev.de> <20181105065807.GA1286@andestech.com> <20181105070551.GA7274@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 05, 2018 at 09:52:52AM +0100, Arnd Bergmann wrote: > > I fundamentally disagree with this… and think it should be the contrary. > > > > 1. The kernel shall support no vendor specific instructions whatsoever, > > period. > > I think what was meant above is > > 1. If a vendor extension requires kernel support, that support > must be able to be built into a kernel image without breaking support > for CPUs that do not have that extension, to allow building a single > kernel image that works on all CPUs. No. This literally means no vendor extensions involving instructions or CSRs in the kernel. They are fine for userspace, or for the M-mode code including impementation of the SBI, but not for the kernel.