From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=2a00:1450:400c:c09::231; helo=mail-wm0-x231.google.com; envelope-from=leif.lindholm@linaro.org; receiver=edk2-devel@lists.01.org Received: from mail-wm0-x231.google.com (mail-wm0-x231.google.com [IPv6:2a00:1450:400c:c09::231]) (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 91C1821F3C1B1 for ; Tue, 10 Oct 2017 14:07:26 -0700 (PDT) Received: by mail-wm0-x231.google.com with SMTP id q132so630804wmd.2 for ; Tue, 10 Oct 2017 14:10:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=TKqDTcocbQAIKzEbI+gSWgHcgQKrfA3XatMrKiQepQE=; b=b9ktwpIyBkibspz+jXW0oBG3FuCaiIIP6PaHapwtbY/KrP/4EAh7SdZ4O77dbqbVYW 2eeTnDRi6TFXvLU0b3k7x0OLzwpKwiu52EnYt0YMr06fE3MSXeR1vSzCd6XLgfgpnMj6 YE1ThiKXX8s99TxmIXguamWKBYUKsLBZDRv7A= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=TKqDTcocbQAIKzEbI+gSWgHcgQKrfA3XatMrKiQepQE=; b=FEM6dBWoGVmWk77KtS8LkBv4WQDAiPIJaY56+gCZmkAAnyH05Qv5aKK1Kxuw5UXL1H M6HE6kZai8XljPMUU3+4Akj471pG09YuaRsDoqocrz58dHMjuZoOUoSz1iPNHlNRLVyQ yNiGYgd63yeBajkDYc679+0yKkZWr+tcozk7J2i/2u36G5DXtfXQ5P3xqAOLXJdYmCoF faYeF2QWWxw8ZhZOz2os7mBOqWvDff6+b4w+kT1ao7wlt6aJRztMxExNFw1b+hNNJVl4 +L/jl8E9JoVLF2F3nuk3oCY7ZVu7tpTZ55+5l4P9rcfffrFHNLI40v+C/QROnXt/P0Xc DAcQ== X-Gm-Message-State: AMCzsaWMHg+a4mwPU7sQMOzUiyFLacLqVR0FHRydbYeJgZADjcFiu4yY 1XZldXnOF9Lwm/wKUWHorliUIA== X-Google-Smtp-Source: AOwi7QB3+R93qJkfwwi9YekGc/T3NW+vCdld5sAWNIK4tOVDyuEpZNtQPZnGbcZIbLJpDS+ycqs3bg== X-Received: by 10.223.147.39 with SMTP id 36mr12864847wro.175.1507669853493; Tue, 10 Oct 2017 14:10:53 -0700 (PDT) Received: from bivouac.eciton.net (bivouac.eciton.net. [2a00:1098:0:86:1000:23:0:2]) by smtp.gmail.com with ESMTPSA id q4sm9850841wmd.19.2017.10.10.14.10.52 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 10 Oct 2017 14:10:52 -0700 (PDT) Date: Tue, 10 Oct 2017 22:10:50 +0100 From: Leif Lindholm To: Ard Biesheuvel Cc: Marcin Wojtas , edk2-devel-01 , Nadav Haklai , Neta Zur Hershkovits , Kostya Porotchkin , Hua Jing , semihalf-dabros-jan Message-ID: <20171010211050.kivb5focjpwqybpz@bivouac.eciton.net> References: <1507568462-28775-1-git-send-email-mw@semihalf.com> <1507568462-28775-9-git-send-email-mw@semihalf.com> <20171010145353.do7b6msel3d25pyu@bivouac.eciton.net> MIME-Version: 1.0 In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Subject: Re: [platforms: PATCH 08/13] Marvell/Armada: Modify GICC alias X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Oct 2017 21:07:27 -0000 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Oct 10, 2017 at 09:45:29PM +0100, Ard Biesheuvel wrote: > On 10 October 2017 at 15:56, Marcin Wojtas wrote: > > Hi Ard, > > > > 2017-10-10 16:53 GMT+02:00 Leif Lindholm : > >> On Mon, Oct 09, 2017 at 07:00:57PM +0200, Marcin Wojtas wrote: > >>> From: Ard Biesheuvel > >>> > >>> The GIC architecture mandates that the CPU interface, which consists > >>> of 2 consecutive 4 KB frames, can be mapped using separate mappings. > >>> Since this is problematic on 64 KB pages, the MMU-400 aliases each > >>> frame 16 times, and the two consecutive frames can be found at offset > >>> 0xf000. This patch is intended to expose correct GICC alias via > >>> MADT, once ACPI support is added. > >> > >> I'm afraid I don't quite understand this message. > >> > >> The change seems to be that the InterfaceBase moves from the first 4KB > >> alias inside a 64KB page to the last alias within the same page. > >> That seems valid, but I don't see how it resolves anything described > >> in this message? > >> > > Because now, GICC + 4 KB will point at the second frame, and so the > two frames appear adjacently, and precisely 4 KB apart. And at the > same time, they are still covered by distinct 64 KB pages so it even > works when running the OS with 64k pages. Right, I was thinking it might be something like that, but I didn't get that from the patch - commit message _or_ comment. Maybe add something like "Use the last alias from the first series of aliases as the base address, so that the first frame from the second series becomes directly adjacent, whilst remaining covered by a separate 64kB page"? / Leif