From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH] Extract initrd free logic from arch-specific code. Date: Wed, 28 Mar 2018 23:14:01 +0100 Message-ID: <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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=im6eBNoLN8sJoeINblQuxwBG+MYWEvTDfpP356YKkAY=; b=tGsVYspHaAVDjH 1X7QYBH2N0/yozSsAXExCY5sT6ud5sipnsl44MyaZFv29tkEVg6cxjeTkWxpy7Sp9mRCUvP5tirFw i/6LyvO3MHg4B7LTK0sauRoRzV1nqPa/XBB5twPleUUiOEeoqPpuzKvm7lK+ATGUl6PZcWX3mFpVf 0RhISQS6bzAMQ1l76CJ8oSi/CW6vj5YcuVTmlPmq8vL17RdQ2ZM4EJGBkGYKddje30WyEI8eUvLu1 Lwm/JclmfxO6bCcCHmE3R2gDHqctmrYcEhoUQ8pe92K7Jd45Ij0Z0xgaHfmV7OylKE7ftQMA7pHIa 0ECnItYdcLsNP3Y2G6pA==; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2014; h=Sender:In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date; bh=R6l9I6PvsGbX3NE2xRpmi4yASMm+0pIHUA/D+Vv+P84=; b=gbjR2kk0bv40X9QfjiyNwJUX+5CjStVha/r8BvT9SY4wV5HUGisePY5s6tPYBYEm0VGPJySPFzIPt/PqVBHN/X6+NGAqj7OwAN0i64GlJcfzglZnIuB0Z9JyJv4qZwv6GBbe2N1ntc/rREwqT2LeBvoTBHZ0VqO3lC+PdYPTz7k=; Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+gla-linux-snps-arc=m.gmane.org@lists.infradead.org To: Rob Landley Cc: linux-mips@linux-mips.org, linux-sh@vger.kernel.org, Benjamin Herrenschmidt , Linus Walleij , Will Deacon , Paul Mackerras , Michael Ellerman , "James E.J. Bottomley" , Christoph Hellwig , Geert Uytterhoeven , Catalin Marinas , Matt Turner , Eugeniy Paltsev , uclinux-h8-devel@lists.sourceforge.jp, Vladimir Murzin , Marc Zyngier , adi-buildroot-devel@lists.sourceforge.net, Al Viro , Thomas Gleixner , Richard Henderson , linux-cris-kernel@axis.com, Greg Kroah-Hartman , linux-kernel@vger.kerne 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 ?) -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up According to speedtest.net: 8.21Mbps down 510kbps up