Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934192Ab3CSWH4 (ORCPT ); Tue, 19 Mar 2013 18:07:56 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:35370 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933133Ab3CSWHz (ORCPT ); Tue, 19 Mar 2013 18:07:55 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: HATAYAMA Daisuke Cc: vgoyal@redhat.com, cpw@sgi.com, kumagai-atsushi@mxc.nes.nec.co.jp, lisa.mitchell@hp.com, heiko.carstens@de.ibm.com, akpm@linux-foundation.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, zhangyanfei@cn.fujitsu.com References: <20130316040003.15064.62308.stgit@localhost6.localdomain6> <20130316040121.15064.35279.stgit@localhost6.localdomain6> Date: Tue, 19 Mar 2013 15:07:47 -0700 In-Reply-To: <20130316040121.15064.35279.stgit@localhost6.localdomain6> (HATAYAMA Daisuke's message of "Sat, 16 Mar 2013 13:01:21 +0900") Message-ID: <87hak7m4b0.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-AID: U2FsdGVkX1+AJ5rM5sREy7TRDevKrDGITh7sKhUIom4= X-SA-Exim-Connect-IP: 98.207.154.105 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.1 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;HATAYAMA Daisuke X-Spam-Relay-Country: Subject: Re: [PATCH v3 06/21] vmcore: round up buffer size of ELF headers by PAGE_SIZE X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Wed, 14 Nov 2012 14:26:46 -0700) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1120 Lines: 26 HATAYAMA Daisuke writes: > To satisfy mmap() page-size boundary requirement, round up buffer size > of ELF headers by PAGE_SIZE. The resulting value becomes offset of ELF > note segments and it's assigned in unique PT_NOTE program header > entry. Ok. That is just silly. You can use a single buffer for the ELF header, the program header and the notes. It just requires a bit of counting ahead of time. The ELF header itself is small, and so are the program headers, especially if you only have one PT_NOTE segment. The only thing that possibly gets big is the note segment, and then that only happens if you have a lot of cpus. Since there are entirely local constructs it seems extremely silly, wasteful and complicated to place each logical part in a separately mmapable buffer instead of placing them in the same mmapable buffer. 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/