From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-x22e.google.com (mail-io0-x22e.google.com [IPv6:2607:f8b0:4001:c06::22e]) (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 BDD5121ECCB28 for ; Wed, 20 Sep 2017 10:35:58 -0700 (PDT) Received: by mail-io0-x22e.google.com with SMTP id v36so5315705ioi.1 for ; Wed, 20 Sep 2017 10:39:04 -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=3zGf41Yj8L3u8lZZRQi23Vc9kl9ETYMRUIVsknXCL6I=; b=JF+AzxWNCAKQ0jz47dQOuPMagjYk1vwoVB7GTIlZDoOcf/CD8PPgeOoOIL+E6nTdm8 KOoUxZuE74bVDYmU7mOCAFLoAchD19zXWjs77IG+9EDYOHvjszt4wZLWy/dofjxbEo2O PrWEcynunXe2I629P5PLotTAQ/VK/vX1kgXO0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=3zGf41Yj8L3u8lZZRQi23Vc9kl9ETYMRUIVsknXCL6I=; b=KZt/Dn6lUGQ10OOj+XGV4wU1E7G5fVSRoaDvGMM0dRU1UCyNJimjmkKMFiEEYoJJpY vOSxEtlnDGDpCocErJAK72AYYAPiBKezIizB2IOzrrIym9x9cFmdx3pzZ/gboglnqNNS RrhIOwFPpHGDdJwhMJhJv7jMG4Oh3H/YqCHqrk7aGJhsgTM277Rg7k5/ZjBpFdH4Nnkt G2IXG19RLh//LyP0h47jWZ9H/HT+rRCDvRGwK14o+Fo1vbc552pccOjmT68zhC3VrHWK D/LmkBbF5njYXTtng5HWxUZmHZhGU31wUWUhjFiyhR7Kj66XA/B1AAJgkhYWBpBwLx/9 vOyg== X-Gm-Message-State: AHPjjUgP+W/df2pD4v/vnJfSVgVmVZOm9cWbOWv2wUcWCf7LYn7ePAO+ V+EVnqzK9rgNNz5f0DBcWoC6BLbz/R5SoVt1rHxwPA== X-Google-Smtp-Source: AOwi7QCSZ4tAqqMDCwrldO6XoZI29174NCjyM2tXAQfRRkAITGWDnliIbfu2zq96jHh2FLf1h7iYN5XiMZNisGfOIts= X-Received: by 10.107.53.213 with SMTP id k82mr8680897ioo.179.1505929144085; Wed, 20 Sep 2017 10:39:04 -0700 (PDT) MIME-Version: 1.0 Received: by 10.107.152.18 with HTTP; Wed, 20 Sep 2017 10:39:03 -0700 (PDT) In-Reply-To: References: <4CC33CC2-86D1-490E-A67E-12D751745121@apple.com> From: Ard Biesheuvel Date: Wed, 20 Sep 2017 10:39:03 -0700 Message-ID: To: Udit Kumar Cc: Pankaj Bansal , Andrew Fish , "Olivier.Martin@arm.com" , Vladimir Olovyannikov , "edk2-devel@lists.01.org" Subject: Re: Storing Non volatile variables on SD/NAND 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: Wed, 20 Sep 2017 17:35:59 -0000 Content-Type: text/plain; charset="UTF-8" On 20 September 2017 at 10:34, Udit Kumar wrote: > > When we want to have UEFI and OS accessing same media , > Possibilities I see > > 1- Patch OS For status check of media (diversion from generic OS), Good case will be modify low level driver. > But we may end up some surprises on synchronization. > > 2- no runtime service for OS . I guess this will not be possible > > 3- Way the Vladimir implemented for eMMC, This has risk of losing data in case of AC power off. > > 4- update hardware with dual view (Ard suggestion) > 5 - abstract direct block device access into a firmware service that is exposed via a DXE_RUNTIME_DRIVER. The UEFI spec allows you to expose entry points into a DXE_RUNTIME_DRIVER module via a UEFI configuration table, and the OS can use a driver that uses the abstracted device rather than the real device. Performance is going to be terrible, probably, and lots of things that are specific to SD/MMC will no longer work, but it is a possibility nonetheless.