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=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 061DEC4363D for ; Tue, 22 Sep 2020 15:26:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A7CB92220D for ; Tue, 22 Sep 2020 15:26:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600788372; bh=fdkOB95sADWwZavkaqHQDRTo4xEzI9y1dh3A7VyjwSI=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=qPBCx8rUakN3V8RHw7ew4G7mvAKvSCkxgfSS+GbsUe8noaMjgbrrtlRnONFANvHIh FVfyTCcuMzCX/IjKTzDyjvky4ZReZ61tAYXBnlPTt72BfraCuDFb0Td0pIXbHmM6bz 1eLBkF9uia1MCyL4gHmpvE6/tOgoYLF/LdHvyFQ0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726643AbgIVP0M (ORCPT ); Tue, 22 Sep 2020 11:26:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:54600 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726614AbgIVP0L (ORCPT ); Tue, 22 Sep 2020 11:26:11 -0400 Received: from mail-oi1-f181.google.com (mail-oi1-f181.google.com [209.85.167.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C9E2B2075E for ; Tue, 22 Sep 2020 15:26:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600788370; bh=fdkOB95sADWwZavkaqHQDRTo4xEzI9y1dh3A7VyjwSI=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=DRW07Ck0X54oFXooGluPImpJUQxiJrEZX8SydAwcJNDEit4ZPd7aNeh3WCed3IVw1 5Z/HwBzre6kfvpeYn9hXZTtGtsalWCynzLQp+B4QvZJudeW2SQUOgvzQPh0ZG2p2Cq CZAHKu2jPTlYbeKY3ep9GS03P/Limp0tLviwbfwQ= Received: by mail-oi1-f181.google.com with SMTP id x69so21412105oia.8 for ; Tue, 22 Sep 2020 08:26:10 -0700 (PDT) X-Gm-Message-State: AOAM533KWrZBqO+8uLa2w4w5hiPnhBSr53ubeMF70A1dOqKmSecUuSRa xxSfDAl/hQX43G0WtePs0SQVKTacVhgDv/pWiBA= X-Google-Smtp-Source: ABdhPJx4ZqpTpDgW9K+kE6zyVU+cMw2Ul74cPwv6oTbT77zPxP5Al0VlHBd3f9rh7ymVVCrOZYe5DhCFYfQYCgV7whc= X-Received: by 2002:a54:4517:: with SMTP id l23mr3082701oil.174.1600788370154; Tue, 22 Sep 2020 08:26:10 -0700 (PDT) MIME-Version: 1.0 References: <20200921154117.757-1-ardb@kernel.org> <20200921154117.757-11-ardb@kernel.org> In-Reply-To: From: Ard Biesheuvel Date: Tue, 22 Sep 2020 17:25:59 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 10/10] ARM: p2v: reduce p2v alignment requirement to 2 MiB To: Nicolas Pitre Cc: Linus Walleij , Linux ARM , linux-efi , Zhen Lei , Russell King Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Tue, 22 Sep 2020 at 17:12, Nicolas Pitre wrote: > > On Tue, 22 Sep 2020, Ard Biesheuvel wrote: > > > By changing the patchable sequences and the patching logic to carry > > more bits of offset, we can improve this: 11 bits gives us 4 GiB >> 11 > > == 2 MiB granularity, and so you never waste more than that amount by > > rounding up the physical start of DRAM to the next multiple of 2 MiB. > > (Note that 2 MiB granularity guarantees that the linear mapping can be > > created efficiently, whereas less than 2 MiB may result in the linear > > mapping needing another level of page tables) > > That is IMHO the top argument for limiting it to 2 MiB. > It would be worth making this explicit in the commit log. > OK, I will merge this paragraph into the commit log.