From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from out03.mta.xmission.com ([166.70.13.233]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UI4hJ-0007tL-SJ for kexec@lists.infradead.org; Tue, 19 Mar 2013 22:07:58 +0000 From: ebiederm@xmission.com (Eric W. Biederman) 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> MIME-Version: 1.0 Subject: Re: [PATCH v3 06/21] vmcore: round up buffer size of ELF headers by PAGE_SIZE List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: HATAYAMA Daisuke Cc: kexec@lists.infradead.org, heiko.carstens@de.ibm.com, linux-kernel@vger.kernel.org, lisa.mitchell@hp.com, kumagai-atsushi@mxc.nes.nec.co.jp, zhangyanfei@cn.fujitsu.com, akpm@linux-foundation.org, cpw@sgi.com, vgoyal@redhat.com 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 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec