Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750860AbWHPGuE (ORCPT ); Wed, 16 Aug 2006 02:50:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750865AbWHPGuE (ORCPT ); Wed, 16 Aug 2006 02:50:04 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:51335 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1750860AbWHPGuC (ORCPT ); Wed, 16 Aug 2006 02:50:02 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: vgoyal@in.ibm.com Cc: linux kernel mailing list , Andi Kleen , Fastboot mailing list , Don Zickus Subject: Re: [PATCH] x86_64: Re-positioning the bss segment References: <20060815214952.GB11719@in.ibm.com> Date: Wed, 16 Aug 2006 00:48:56 -0600 In-Reply-To: <20060815214952.GB11719@in.ibm.com> (Vivek Goyal's message of "Tue, 15 Aug 2006 17:49:52 -0400") Message-ID: User-Agent: Gnus/5.110004 (No Gnus v0.4) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1810 Lines: 39 Vivek Goyal writes: > o Currently bss segment is being placed somewhere in the middle (after .data) > section and after bss lots of init section and data sections are coming. > Is it intentional? > > o One side affect of placing bss in the middle is that objcopy keeps the > bss in raw binary image (vmlinux.bin) hence unnecessarily increasing > the size of raw binary image. (In my case ~600K). It also increases > the size of generated bzImage, though the increase is very small > (896 bytes), probably a very high compression ratio for stream > of zeros. > > o This patch moves the bss at the end hence reducing the size of > bzImage by 896 bytes and size of vmlinux.bin by 600K. > > o This change benefits in the context of relocatable kernel patches. If > kernel bss is not part of compressed data (vmlinux.bin) then it does > not have to be decompressed and this area can be used by the decompressor > for its execution hence keeping the memory requirements bounded and > decompressor code does not stomp over any other data loaded beyond > kernel image (As might be the case with bootloaders like kexec). Looks sane here. I don't know if there are any side effects from placing the .bss after the .init sections that we discard at after boot. Unless this has undesirable side effects this should have us doing the expected thing, with the .bss section which is less likely to confuse people in general. > Signed-off-by: Vivek Goyal Acked-by: Eric Biederman Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/