From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 13282 invoked by alias); 24 Dec 2004 15:00:17 -0000 Mailing-List: contact binutils-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: binutils-owner@sources.redhat.com Received: (qmail 13259 invoked from network); 24 Dec 2004 15:00:11 -0000 Received: from unknown (205.217.158.180) by sourceware.org with QMTP; 24 Dec 2004 15:00:11 -0000 Received: (qmail 17868 invoked by uid 10); 24 Dec 2004 15:00:10 -0000 Received: (qmail 1876 invoked by uid 500); 24 Dec 2004 14:59:58 -0000 Mail-Followup-To: binutils@sources.redhat.com, simonb@wasabisystems.com To: Simon Burge Cc: binutils@sources.redhat.com Subject: Re: .eh_frame section on alpha References: <20041224132148.GA17654@thoreau.thistledown.com.au> From: Ian Lance Taylor Date: Fri, 24 Dec 2004 15:00:00 -0000 In-Reply-To: <20041224132148.GA17654@thoreau.thistledown.com.au> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-SW-Source: 2004-12/txt/msg00304.txt.bz2 Simon Burge writes: > http://sources.redhat.com/ml/binutils/2003-05/msg00863.html added the > generation of a .eh_frame section to all objects that otherwise didn't > have them. > > On NetBSD, we have some tight code size constraints for our first stage > boot loader - it needs to fit in 7.5k of space at the start of the disk. > With binutils 2.14, our boot loader was 6880 bytes. With binutils 2.15, > the boot loader is 7848. The only difference in size between the two is > the .eh_frame section: > > 3 .eh_frame 000003c4 0000000020001990 0000000020001990 00001a40 2**3 > CONTENTS, ALLOC, LOAD, READONLY, DATA > > What exactly is this section used for? A bit of googling seems to > indicate it's for exception handling, which isn't a C issue. > > More importantly, how can I disable the generation of this section? It > seems that only alpha generates an .eh_frame section unconditionally. Hi Simon. I haven't tested it, but there should be two ways to disable to automatic creation of the .eh_frame section: 1) do not emit the directives which create one--.ent, .end, .frame, etc.; 2) create your own .eh_frame section and put nothing in it--for example, the assembler doesn't generate its own unwind information for compiled code, because the compiler creates a .eh_frame section anyhow. However, I also think it would be a good idea to have an assembler option to not create the unwind information. Ian