From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-x229.google.com (mail-it0-x229.google.com [IPv6:2607:f8b0:4001:c0b::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id E46271A1DEE for ; Thu, 8 Sep 2016 02:39:19 -0700 (PDT) Received: by mail-it0-x229.google.com with SMTP id c198so69966836ith.1 for ; Thu, 08 Sep 2016 02:39:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=+xLWI49RcDB5HX8cxEtfSziaphD+K8hVTVeyZbQlDtE=; b=crGmopgJpW/5D76bgF+qtvJFqUJioLaexLPWz6ub4D04bptEftW0uOamCuGiaO5M3s dSpPlaroVR/kcTWuI80ZTA7epzTGcfj6xFwtkXFU2U9WRRq1e2vt3Tdwlg2bfBflEEt2 foTm1wJCkjNV/8PvBhPS25MSCXypR5pEGRy34= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=+xLWI49RcDB5HX8cxEtfSziaphD+K8hVTVeyZbQlDtE=; b=PPpCtmCXneZ5/el6K8pmNkLVxIU+RpAPFs5mGjZpsYcHJy2Mp7AqX3FpWraiC6INKe zNmHT1YLei1tfjplrsRc0ImBXeN/dsLYk5HGAhcrCK5v5OmF6JZfMbbf23D7kI/j6Vy5 2ovidx7+ERtmt5iUGOOZz0jHzfMyxssHJ66qGIem+AJgxHSdbj2GNnBsrxuHaZ4r5RzK MDyf7H0e5vqpkYLToMo0+ozveJvw+kFumFcthZIDlrefaCZesCKGem9LARXOJxuekdf3 IbNgEw4D4Q5vKsRdvfin1RkMZTE8FZvEGV51YL3Y8w79XvxuCWTEUyxkf9zTKYk0RLW+ f6Hg== X-Gm-Message-State: AE9vXwPbMxKXwHfKj9q+/HPiEi324S29//WNAyNAEhOkscFQb1KlbFtYH3naSnsZwj28AXgoxEvBiXtnOw5tJ5iJ X-Received: by 10.36.29.14 with SMTP id 14mr14469694itj.87.1473327559237; Thu, 08 Sep 2016 02:39:19 -0700 (PDT) MIME-Version: 1.0 Received: by 10.36.204.195 with HTTP; Thu, 8 Sep 2016 02:39:18 -0700 (PDT) In-Reply-To: <20160908092153.GH16080@bivouac.eciton.net> References: <1473322418-9158-1-git-send-email-ard.biesheuvel@linaro.org> <20160908092153.GH16080@bivouac.eciton.net> From: Ard Biesheuvel Date: Thu, 8 Sep 2016 10:39:18 +0100 Message-ID: To: Leif Lindholm Cc: edk2-devel-01 Subject: Re: [PATCH] ArmPlatformPkg: remove EFI_MEMORY_UC attribute from normal memory X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 08 Sep 2016 09:39:20 -0000 Content-Type: text/plain; charset=UTF-8 On 8 September 2016 at 10:21, Leif Lindholm wrote: > On Thu, Sep 08, 2016 at 09:13:38AM +0100, Ard Biesheuvel wrote: >> On ARM systems, mapping normal memory as device memory may have unintended >> side effects, given that unaligned accesses or loads and stores with special >> semantics (e.g., load/store exclusive) may fault or may not work as expected. >> Similarly, DC ZVA instructions are only supported on normal memory, not >> device memory. > > I think this is the right thing to do; Arguably, on the modern ARM > architectures, UNCACHEABLE and WRITE_COMBINEABLE are mutually > exclusive. I'll discuss with Charles whether we should codify this in > the UEFI specification. > >> So remove the EFI_MEMORY_UC attribute that we set by default on system RAM. >> If any region requires this attribute, it is up to the driver to set this >> attribute, and to ensure that no offending operations are performed on it. >> >> Contributed-under: TianoCore Contribution Agreement 1.0 >> Signed-off-by: Ard Biesheuvel > > Reviewed-by: Leif Lindholm > Pushed, thanks. I will follow up with similar patches for OpenPlatformPkg