From owner-freebsd-current Thu Jul 31 17:08:53 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id RAA12304 for current-outgoing; Thu, 31 Jul 1997 17:08:53 -0700 (PDT) Received: from mail.cdsnet.net (mail.cdsnet.net [204.118.244.5]) by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id RAA12297 for ; Thu, 31 Jul 1997 17:08:50 -0700 (PDT) Received: from chop.cdsnet.net (chop.cdsnet.net [204.118.244.3]) by mail.cdsnet.net (8.8.6/8.8.6) with ESMTP id RAA15967; Thu, 31 Jul 1997 17:08:49 -0700 (PDT) Received: from nowin (1Cust116.max3.boston.ma.ms.uu.net [153.35.70.244]) by chop.cdsnet.net (8.8.5/8.8.5) with SMTP id RAA08430; Thu, 31 Jul 1997 17:08:45 -0700 (PDT) Message-Id: <3.0.3.32.19970731194947.030b5044@ranier.altavista-software.com> X-Sender: 3ampop@ranier.altavista-software.com X-Mailer: QUALCOMM Windows Eudora Pro Version 3.0.3 (32) Date: Thu, 31 Jul 1997 19:49:47 -0400 To: Terry Lambert From: Matt Thomas Subject: Re: core group topics Cc: freebsd-current@freefall.FreeBSD.org In-Reply-To: <199707312022.NAA07684@phaeton.artisoft.com> References: <199707311142.EAA28471@implode.root.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: owner-freebsd-current@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk At 01:22 PM 7/31/97 -0700, Terry Lambert wrote: >> >Are we getting the kernel & userland mixed up here ? I belive there >> >is strong agreement for ELF for the kernel... >> >> There is? I don't recall discussing that at all, and if we do eventually go >> the ELF way, I think the kernel would be one of the last areas we'd want to >> convert since it further complicates our cramped bootblocks. > >This is only true if you maintain support for booting non-ELF kernels; >I view this as more of a transition issue than anything else. > > >> The only issue I have against ELF is that I'm concerned that the overhead >> for processing the much more sophisticated header at exec time might have a >> serious impact on exec performance (something I'm particularly sensitive to >> since I wrote the a.out exec code for FreeBSD). > >This is a bvery good point. But I think the benefits outweigh the >costs. In particualr, the kernel could map the ld.so instead of >making the crt0.o do it; this would buy back some of the overhead >right away, if it stayed mapped in the cloned porcess address space >from the fork to the exec. The same is actually true of the libc.so >and other shared libraries, albiet a bit of an arbitrary mapping >stretch (ie: pick a high address and map down). Specifically, I'd >only place libc in this boat, seeing as how few programs can exist >without system calls of one kind or another. That's how NetBSD does it. It loads the executable and the interpt. (ld-elf.so) and transfers controls to the interpt instead of the executable. -- Matt Thomas Internet: matt@3am-software.com 3am Software Foundry WWW URL: http://www.3am-software.com/bio/matt.html Nashua, NH Disclaimer: I disavow all knowledge of this message