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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF670C433FE for ; Wed, 24 Nov 2021 12:18:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244040AbhKXMV3 convert rfc822-to-8bit (ORCPT ); Wed, 24 Nov 2021 07:21:29 -0500 Received: from gloria.sntech.de ([185.11.138.130]:32908 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242398AbhKXMTZ (ORCPT ); Wed, 24 Nov 2021 07:19:25 -0500 Received: from ip5f5b2004.dynamic.kabel-deutschland.de ([95.91.32.4] helo=diego.localnet) by gloria.sntech.de with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mprCA-0005IV-G5; Wed, 24 Nov 2021 13:16:14 +0100 From: Heiko =?ISO-8859-1?Q?St=FCbner?= To: linux-riscv@lists.infradead.org Cc: Anup Patel , Palmer Dabbelt , atishp@rivosinc.com, linux-riscv , Linux Kernel Mailing List , Linux Doc Mailing List , Guo Ren , Philipp Tomsich , Guo Ren Subject: Re: [RFC PATCH 0/3] riscv: Add riscv.fwsz kernel parameter to save memory Date: Wed, 24 Nov 2021 13:16:13 +0100 Message-ID: <6883721.WJZ4dBXcaH@diego> In-Reply-To: References: <20211123015717.542631-1-guoren@kernel.org> <1913356.JkcO0Xq8vV@diego> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="iso-8859-1" Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Am Mittwoch, 24. November 2021, 07:42:17 CET schrieb Guo Ren: > On Wed, Nov 24, 2021 at 3:33 AM Heiko Stübner wrote: > > > > Hi Guo, > > > > Am Dienstag, 23. November 2021, 02:57:14 CET schrieb guoren@kernel.org: > > > From: Guo Ren > > > > > > The firmware of riscv (such as opensbi) occupy 2MB(64bit) / > > > 4MB(32bit) in Linux. It's very wasteful to small memory footprint > > > soc chip such as Allwinner D1s/F133. The kernel parameter gives a > > > chance to users to set the proper size of the firmware and get > > > more than 1.5MB of memory. > > > > is this kernel parameter approach a result of the T-Head Ice-SoC > > currently loading its openSBI from inside the main u-boot via extfs-load, > > directly before the kernel itself [0] ? > The patch is not related to that issue. The patch just helps users who > put opensbi at 0~2MB paddr to save memory. So as Anup wrote, this should just be solved by using a correct reserved memory node in the devicetree passed to the kernel. And the firmware will know what memory region it actually occupies ;-) > > > > > Because that approach in general looks not ideal. > > > > Normally you want the main u-boot already running with less privileges > > so firmware like openSBI should've been already loaded before that. > > Even more true when you're employing methods to protect memory regions > > from less privileged access. > > > > A lot of socs set u-boot as opensbi payload, but for the example the D1 > > mainline approach uses the Allwinner TOC1 image format to load both > > opensbi and the main uboot into memory from its 1st stage loader. > > > > > > Of course the best way would be to just mimic what a number of > > arm64 and also riscv socs do and use already existing u-boot utilities. > > > > U-Boot can create a FIT image containing both main u-boot, dtb and > > firmware images that all get loaded from SPL and placed at the correct > > addresses before having the SPL jump into opensbi and from there > > into u-boot [1] . > > > > And as Anup was writing, reserved-memory should then be the way > > to go to tell the kernel what regions to omit. > > > > And mainline u-boot has already the means to even take the reserved-memory > > from the devicetree used by opensbi and copy it to a new devicetree, > > if the second one is different. > > > > > > Heiko > > > > > > [0] https://github.com/T-head-Semi/u-boot/blob/main/include/configs/ice-c910.h#L46 > > [1] see spl_invoke_opensbi() in common/spl/spl_opensbi.c > > [2] see riscv_board_reserved_mem_fixup() in arch/riscv/lib/fdt_fixup.c > > > > > > > > Guo Ren (3): > > > riscv: Remove 2MB offset in the mm layout > > > riscv: Add early_param to decrease firmware region > > > riscv: Add riscv.fwsz kernel parameter > > > > > > .../admin-guide/kernel-parameters.txt | 3 +++ > > > arch/riscv/include/asm/page.h | 8 +++++++ > > > arch/riscv/kernel/head.S | 10 +++----- > > > arch/riscv/kernel/vmlinux.lds.S | 5 ++-- > > > arch/riscv/mm/init.c | 23 ++++++++++++++++--- > > > 5 files changed, 36 insertions(+), 13 deletions(-) > > > > > > > > > > > > > > > > >