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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 EDD37C4338F for ; Mon, 9 Aug 2021 17:27:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D233F60EDF for ; Mon, 9 Aug 2021 17:27:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234234AbhHIR1X (ORCPT ); Mon, 9 Aug 2021 13:27:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57938 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233919AbhHIR1X (ORCPT ); Mon, 9 Aug 2021 13:27:23 -0400 Received: from sipsolutions.net (s3.sipsolutions.net [IPv6:2a01:4f8:191:4433::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F292DC0613D3 for ; Mon, 9 Aug 2021 10:27:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=Content-Transfer-Encoding:MIME-Version: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=4DDX4MJfPISPRbp4j7HoYkMuGx5m46aMi+yyP2A3MD8=; t=1628530023; x=1629739623; b=Ttqadvrlg/m/w2GYC8Kj2smOghJXU+RierFtDXZUKvPU88J gfSAgBak/HdBxDzQhOaZBX8eYs7tSpF+md8M1lRKuozZ+hGUVT0ZhNKvnT7gggNaVKy61rGj6g5k3 Sw2wnFH6CgbFnzlwu/XJSrdk8cq/CeDtf+7C1l3bJu8cwhYa3PzpidSt3yaatlHwM/CcCx4dwzaf3 bNsyWVCH2KzezLZLy10/EpOUOpjeFyRouXLbIg2BDFXib5wc87BPqThVBojQXJQ4gYqA0j+rOM35V HfXOG3ROFdc4aJXV7EXq9yTnJcmsoHaeJwVbO9ivaT2UwITv0IsMOn8g5XDCmssA==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94.2) (envelope-from ) id 1mD90d-008D6r-UQ; Mon, 09 Aug 2021 19:26:58 +0200 Message-ID: <0ef27e7c8df520ca48900140b3930af279cd2466.camel@sipsolutions.net> Subject: Re: [PATCH] dmaengine: ioat: depends on !UML From: Johannes Berg To: Dan Williams Cc: Dave Jiang , dmaengine@vger.kernel.org, Geert Uytterhoeven Date: Mon, 09 Aug 2021 19:26:57 +0200 In-Reply-To: References: <20210809112409.a3a0974874d2.I2ffe3d11ed37f735da2f39884a74c953b258b995@changeid> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.4 (3.38.4-1.fc33) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-malware-bazaar: not-scanned Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On Mon, 2021-08-09 at 10:24 -0700, Dan Williams wrote: > On Mon, Aug 9, 2021 at 2:25 AM Johannes Berg wrote: > > > > From: Johannes Berg > > > > Now that UML has PCI support, this driver must depend also on > > !UML since it pokes at X86_64 architecture internals that don't > > exist on ARCH=um. > > > > Do you really need to disable compilation of the whole driver just > because an arch level helper does not exist on UML builds? Isn't there > already a check for enqcmds on x86_64 to make sure the CPU is > sufficiently feature enabled? Hmm? The problem here is that cpuid_eax() and cpuid_ebx() don't even exist on UML, and that's not really surprising - ARCH=um is after all compiled to run as a userspace process, not to run on bare metal. I guess technically we could provide (fake or even sort of real) implementations of these, but there's very little point? I don't see why you would ever possibly want to have this driver compiled on ARCH=um, even if it's compiled for x86-64 "subarch", since there will be no such device to run against? johannes