From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1522276673; cv=none; d=google.com; s=arc-20160816; b=dgMh7uNnQ+06gJcq4BpmoVkV5vl4tVe7QbOXhd3Y0U/g2LR7stO3r4zGIhCocD7E7O U5AnhQTzDe4k/wOIFyncEUSqHZ/MWwE9LDmz1b38TY1igl/IMdWn43BoSr8Lb70fXkir yGE+KHYAFCDIP+PWa+KeEpDyGzt8KnkrM2sm6iclC4QNHYO1/uQPNHbRoWRXLnyj3nZQ O/ac4Sc9sNaZcwV4QsvFhwZMuKW2pYXeP8feCrccun7I8pZGN1WiShgJBDfz8S6himPS x3D5hOqSlN6kN3Rmcsytaa2qaBcnQp85I6CArJWqS8MKIKS2qUtVl/9Uvg6qBLr7FF/d DtEA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:references:in-reply-to :mime-version:dkim-signature:arc-authentication-results; bh=nnpD6Ps7J34/xAmwZTUnUReer7G77oJS7ENxTSotV08=; b=J6m3tQB9BVO2irDrQVRq9hi9+usD9qDR27y99YcSDeO0QbpsvbuPPSPczzCJfKBuhz UUiX/UUwwItmpNwxiO3mg1DP0HJYfoJnMFub/LqWvmyaofwACbhtqinJ3uiKKO7chYOu GNFMueaHVJjHEOLxUbD0zER/sZYmR0oVW4g6nWDiGR5c7/ndtXucK//+hRudwEkWq597 ZRomaAn3cuNdqKz0Nzs/gCn6U9H23kufeKGagAhncoyhSqeEyN6jUWjhTE/xgDnrpuMb ENWvUwafF8unUuP4wjUPnOJh0boSuMt5wOQNTAbM+5g7+IwtImpYdtmyTPZgTI7Z6AAF YJcw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=aigf+O1P; spf=pass (google.com: domain of oohall@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=oohall@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=aigf+O1P; spf=pass (google.com: domain of oohall@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=oohall@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com X-Google-Smtp-Source: AIpwx49Tp5WOtIT8plg8EStL/Cdmar1UzEeBs4CuNuZHJkUufEESEMcUIZSsckiYwV/tePND2F0fGdU+RZ4AHKcml90= MIME-Version: 1.0 In-Reply-To: <20180328221401.GA14084@n2100.armlinux.org.uk> References: <20180325221853.10839-1-shea@shealevy.com> <20180328152714.6103-1-shea@shealevy.com> <05620fee-e8b5-0668-77b8-da073dc78c40@landley.net> <20180328164813.GA3888@n2100.armlinux.org.uk> <20180328221401.GA14084@n2100.armlinux.org.uk> From: Oliver Date: Thu, 29 Mar 2018 09:37:52 +1100 Message-ID: Subject: Re: [PATCH] Extract initrd free logic from arch-specific code. To: Russell King - ARM Linux Cc: Rob Landley , Shea Levy , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Christoph Hellwig , Richard Henderson , Ivan Kokshaysky , Matt Turner , Vineet Gupta , Catalin Marinas , Will Deacon , Mark Salter , Aurelien Jacquiot , Mikael Starvik , Jesper Nilsson , Yoshinori Sato , Richard Kuo , Tony Luck , Fenghua Yu , Geert Uytterhoeven , James Hogan , Michal Simek , Ralf Baechle , David Howells , Ley Foon Tan , Jonas Bonn , Stefan Kristiansson , Stafford Horne , "James E.J. Bottomley" , Helge Deller , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Palmer Dabbelt , Albert Ou , Martin Schwidefsky , Heiko Carstens , Chen Liqin , Lennox Wu , Rich Felker , "David S. Miller" , Jeff Dike , Richard Weinberger , Guan Xuetao , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Chris Zankel , Max Filippov , Kate Stewart , Greg Kroah-Hartman , Philippe Ombredanne , Eugeniy Paltsev , Al Viro , Vladimir Murzin , Linus Walleij , Michal Hocko , Andrew Morton , Sudip Mukherjee , Marc Zyngier , Rob Herring , Kees Cook , Vlastimil Babka , Balbir Singh , Christophe Leroy , Joe Perches , Dan Williams , Wei Yang , =?UTF-8?Q?Christian_K=C3=B6nig?= , Arnd Bergmann , Deepa Dinamani , Daniel Thompson , Florian Fainelli , linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, adi-buildroot-devel@lists.sourceforge.net, linux-c6x-dev@linux-c6x.org, linux-cris-kernel@axis.com, uclinux-h8-devel@lists.sourceforge.jp, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, linux-am33-list@redhat.com, nios2-dev@lists.rocketboards.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev , linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net, user-mode-linux-user@lists.sourceforge.net, linux-xtensa@linux-xtensa.org, Nicholas Piggin Content-Type: text/plain; charset="UTF-8" X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1596195734883590774?= X-GMAIL-MSGID: =?utf-8?q?1596222784740931526?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Thu, Mar 29, 2018 at 9:14 AM, Russell King - ARM Linux wrote: > On Wed, Mar 28, 2018 at 02:04:22PM -0500, Rob Landley wrote: >> >> >> On 03/28/2018 11:48 AM, Russell King - ARM Linux wrote: >> > On Wed, Mar 28, 2018 at 10:58:51AM -0500, Rob Landley wrote: >> >> On 03/28/2018 10:26 AM, Shea Levy wrote: >> >>> Now only those architectures that have custom initrd free requirements >> >>> need to define free_initrd_mem. >> >> ... >> >>> --- a/arch/arc/mm/init.c >> >>> +++ b/arch/arc/mm/init.c >> >>> @@ -229,10 +229,3 @@ void __ref free_initmem(void) >> >>> { >> >>> free_initmem_default(-1); >> >>> } >> >>> - >> >>> -#ifdef CONFIG_BLK_DEV_INITRD >> >>> -void __init free_initrd_mem(unsigned long start, unsigned long end) >> >>> -{ >> >>> - free_reserved_area((void *)start, (void *)end, -1, "initrd"); >> >>> -} >> >>> -#endif >> >>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig >> >>> index 3f972e83909b..19d1c5594e2d 100644 >> >>> --- a/arch/arm/Kconfig >> >>> +++ b/arch/arm/Kconfig >> >>> @@ -47,6 +47,7 @@ config ARM >> >>> select HARDIRQS_SW_RESEND >> >>> select HAVE_ARCH_AUDITSYSCALL if (AEABI && !OABI_COMPAT) >> >>> select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6 >> >>> + select HAVE_ARCH_FREE_INITRD_MEM >> >>> select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU >> >>> select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU >> >>> select HAVE_ARCH_MMAP_RND_BITS if MMU >> >> >> >> Isn't this why weak symbols were invented? >> > >> > Weak symbols means that we end up with both the weakly-referenced code >> > and the arch code in the kernel image. That's fine if the weak code >> > is small. >> >> The kernel's been able to build with link time garbage collection since 2016: >> >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b67067f1176d >> >> Wouldn't that remove the unused one? > > Probably, if anyone bothered to use that, which they don't. > > LD_DEAD_CODE_DATA_ELIMINATION is a symbol without a prompt, and from > what I can see, nothing selects it. Therefore, the symbol is always > disabled, and so the feature never gets used in mainline kernels. > > Brings up the obvious question - why is it there if it's completely > unused? (Maybe to cause confusion, and allowing a justification > for __weak ?) IIRC Nick had some patches to do the arch enablement for powerpc, but I'm not sure what happened to them though. I suspect it just fell down Nick's ever growing TODO list.