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[2620:137:e000::1:20]) by mx.google.com with ESMTP id h11-20020a170902748b00b001adc3a1b3fasi2034504pll.282.2023.05.11.07.27.23; Thu, 11 May 2023 07:27:46 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b="jcQ8/lb8"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237867AbjEKOXp (ORCPT + 99 others); Thu, 11 May 2023 10:23:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42410 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238271AbjEKOXg (ORCPT ); Thu, 11 May 2023 10:23:36 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34BBA5FD2; Thu, 11 May 2023 07:23:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C4B6A614F5; Thu, 11 May 2023 14:23:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AFE3FC4339B; Thu, 11 May 2023 14:23:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683814998; bh=ttH63jm3oRXZocNrzbxAhA7UBN+8YVEox9ekGGVcYR4=; h=From:To:Cc:Subject:Date:From; b=jcQ8/lb8jG/eXSbSQ+XOukeP6fiMjxMNAHRGswnfJWJSA8ZN9cYOCk8QF4TgIHCyK CVaTJdz6iQhaAR8iGuUbjl9RB8PGFnAI2K/gHl1dpN8NzcGq/3Elxa5NKBdh0tvhlu yHxluj4e9zLA5rMniU07TSvx8XWgFBdCzzIPzqX9w9U02uEyY0uZCHGK5G+I1chxw0 /UET0S2RPJisdLI94Q9oZFTkqO9dd6bCDMJqGhZHirBWBIrnQ/tqCW+XPfI1brvo2i VyqAon31aX+YIDTDFwKxoffiHCWUPF82DmlXhbULi2SE2onh3N++hf6CCaGQ1Mc7yD Yx+aWDbkTfHIw== From: Jisheng Zhang To: Paul Walmsley , Palmer Dabbelt , Albert Ou , Arnd Bergmann Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: [PATCH 0/4] riscv: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION Date: Thu, 11 May 2023 22:12:07 +0800 Message-Id: <20230511141211.2418-1-jszhang@kernel.org> X-Mailer: git-send-email 2.40.0 MIME-Version: 1.0 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1765608276799654436?= X-GMAIL-MSGID: =?utf-8?q?1765608276799654436?= When trying to run linux with various opensource riscv core on resource limited FPGA platforms, for example, those FPGAs with less than 16MB SDRAM, I want to save mem as much as possible. One of the major technologies is kernel size optimizations, I found that riscv does not currently support HAVE_LD_DEAD_CODE_DATA_ELIMINATION, which passes -fdata-sections, -ffunction-sections to CFLAGS and passes the --gc-sections flag to the linker. This not only benefits my case on FPGA but also benefits defconfigs. Here are some notable improvements from enabling this with defconfigs: nommu_k210_defconfig: text data bss dec hex 1112009 410288 59837 1582134 182436 before 962838 376656 51285 1390779 1538bb after rv32_defconfig: text data bss dec hex 8804455 2816544 290577 11911576 b5c198 before 8692295 2779872 288977 11761144 b375f8 after defconfig: text data bss dec hex 9438267 3391332 485333 13314932 cb2b74 before 9285914 3350052 483349 13119315 c82f53 after patch1 and patch2 are clean ups. patch3 fixes a typo. patch4 finally enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION for riscv. Jisheng Zhang (4): riscv: vmlinux-xip.lds.S: remove .alternative section riscv: move HAVE_RETHOOK to keep entries sorted riscv: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION vmlinux.lds.h: use correct .init.data.* section name arch/riscv/Kconfig | 3 ++- arch/riscv/kernel/vmlinux-xip.lds.S | 6 ------ arch/riscv/kernel/vmlinux.lds.S | 6 +++--- include/asm-generic/vmlinux.lds.h | 2 +- 4 files changed, 6 insertions(+), 11 deletions(-)