From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ej1-x636.google.com (mail-ej1-x636.google.com [IPv6:2a00:1450:4864:20::636]) by sourceware.org (Postfix) with ESMTPS id 852893949E2E for ; Sun, 18 Dec 2022 22:44:55 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 852893949E2E Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-ej1-x636.google.com with SMTP id m18so17716863eji.5 for ; Sun, 18 Dec 2022 14:44:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=5XGJ+nP/i/4A38t/EWwdufF7XfvnO/qL1w6m3X+ZOko=; b=JqBcRPAELU9PqYl0px97hnrS3U4uVLL7dsLxW5uvJ7sfloh8bPkfAqkkXrmlji58Bg xmRXwErmeAtRNHvyFQLXQN1lGiQQEYlbI4yw05PwACeuffBCCY1PR0pRpql6dWf5uCrt bTupKMy58Je8eIig0VQUJyXLHrlrId7F418MkXiTWCOoOd9iIA+cIpfJsxbgraWM66/+ JUJXERs8ZtsyTiLFdWXboROMonkiqwsf3qQrVrGX13rZ4lcco6N+16q91yuvw38lGmjq Z2zg3y6zBkkeGED8TSaQDE/ifppcjt2/sukUxYuKMo595pmcCpyjE6RtV1bqdq0MDg5Z R6xg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=5XGJ+nP/i/4A38t/EWwdufF7XfvnO/qL1w6m3X+ZOko=; b=Y9EtctamxWwcQwywfpPkkIx+YC2UoH4jlJl8edhHp7xN2TEuumqp0hUiomX9dwdYmZ 4XlXHYQgZSJfZ9m8Jxv9713KDNyphO4HEbOzo0YeSxkoRoHsqNhKWWV+cp85NRkgTauZ KTQM2qFavnmYrq87RfRoryF5aGUSnHmAtfpbGQNoo3WA3MlFZoRlL+Q8zP6ztiyXltxS CDV/pW7CBfbNlhzNm3u7vuoDQSvCLhb726RDe/w0OS4ZdwWyBGN1hik5QB97iILzGCmX 0TNWWuOd5HIH2raRCJ74IYel0SugAX50GG8qzyjp9ENzCGmItcTLFo3EGt7A1OItht4r Vuew== X-Gm-Message-State: ANoB5pn/v3y+z429YMkzdzVrxXwcp1X5kjGOYROY+ohi1DZr6yhY1qig X7KS1cMufWQLhWQf0yoUT6nuanpwNMo7a8pnARQ= X-Google-Smtp-Source: AA0mqf7M7llroVfYX2GL2z4iO3SnHg0BQWCqSFqobgjZdVdBB/u5PRQVgLFETfqwddYDjx44ILc/6gY9WDRsHw5XlTk= X-Received: by 2002:a17:906:9615:b0:7c0:f459:a0e4 with SMTP id s21-20020a170906961500b007c0f459a0e4mr15907484ejx.155.1671403494193; Sun, 18 Dec 2022 14:44:54 -0800 (PST) MIME-Version: 1.0 References: <20221216214310.13155-1-prabhakar.mahadev-lad.rj@bp.renesas.com> <20221218062404.cn75smc4pperrsd7@gmail.com> In-Reply-To: <20221218062404.cn75smc4pperrsd7@gmail.com> From: "Lad, Prabhakar" Date: Sun, 18 Dec 2022 22:44:28 +0000 Message-ID: Subject: Re: [RFC PATCH] ld/emulparams: elf32lriscv-defs: Add support tune the text segment start address To: Fangrui Song Cc: Lad Prabhakar , Palmer Dabbelt , Andrew Waterman , Jim Wilson , Nelson Chu , binutils@sourceware.org Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-7.0 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Hi Fangrui, Thank you for the feedback. On Sun, Dec 18, 2022 at 6:24 AM Fangrui Song wrote: > > On 2022-12-16, Lad Prabhakar via Binutils wrote: > >On the RISC-V architecture the TEXT_START_ADDR defaults to 0x10000. On > >some RISC-V platforms we want to set this offset to something else. So > >this patch provides a way to tune the text segment start address. > >elf32lriscv-defs.sh now checks for DEFAULT_TEXT_START_ADDR variable and > >if being set it overrides TEXT_START_ADDR to the value set by > >DEFAULT_TEXT_START_ADDR or else defaults to 0x10000. > > > >Renesas RZ/Five RISC-V SoC has Instruction local memory and Data local > >memory (ILM & DLM) which maps between region 0x30000 - 0x4FFFF. When the > >virtual address falls in this range the MMU doesn't trigger a page > >fault and assumes the virtual address as physical address and causes > >undesired behaviours of statically applications/libraries. Hence introduce > >an option to tune the TEXT_START_ADDR. > > > >Signed-off-by: Lad Prabhakar > >--- > >Hi All, > > > >This patch is inspired from the current ld/emulparams/nds32elf_linux.sh file > >where similar approach is being used and DEFAULT_TEXT_START_ADDR variable is > >checked to adjust the TEXT_START_ADDR for the platform. > > > >I am not sure if this is the right approach the above issue has been discussed > >on the ML [0]. > > > >[0] https://sourceware.org/pipermail/binutils/2022-November/124813.html > > > >Cheers, > >Prabhakar > >--- > > ld/emulparams/elf32lriscv-defs.sh | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > >diff --git a/ld/emulparams/elf32lriscv-defs.sh b/ld/emulparams/elf32lriscv-defs.sh > >index b823cedacab..026aef4714b 100644 > >--- a/ld/emulparams/elf32lriscv-defs.sh > >+++ b/ld/emulparams/elf32lriscv-defs.sh > >@@ -27,7 +27,11 @@ case "$target" in > > esac > > > > IREL_IN_PLT= > >-TEXT_START_ADDR=0x10000 > >+if [ -z ${DEFAULT_TEXT_START_ADDR+x} ]; then > >+ TEXT_START_ADDR=0x10000 > >+else > >+ TEXT_START_ADDR=$DEFAULT_TEXT_START_ADDR > >+fi > > MAXPAGESIZE="CONSTANT (MAXPAGESIZE)" > > COMMONPAGESIZE="CONSTANT (COMMONPAGESIZE)" > > > >-- > >2.17.1 > > > > Changing ld does not look like a good change to me. This tuning can be > placed at the compiler driver side as that is the usual place to tune > these things. We can ask users to specify -Wl,-Ttext-segment= (with lld > use --image-base= instead) . With the above approach we will have to target each and individual application/library that is statically compiled. > If that is inconvenient, with Clang you can > add the option to a configuration file > (https://clang.llvm.org/docs/UsersManual.html#configuration-files). > With GCC there may be an option to add a fragment to the default specs > file. I'm more specifically concerned about yocto/debian builds which use GCC. With the proposed approach the changes are central and we can make sure everything will fall in place for yocto/debian rootfs builds with a single change. Also what I get from Palmer is that moving forward we want to adjust the TEXT_START_ADDR based on the page size (Huge page). Cheers, Prabhakar