From owner-freebsd-current Fri Dec 13 16:45:23 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4C73B37B401; Fri, 13 Dec 2002 16:45:21 -0800 (PST) Received: from canning.wemm.org (canning.wemm.org [192.203.228.65]) by mx1.FreeBSD.org (Postfix) with ESMTP id 09BFC43ED1; Fri, 13 Dec 2002 16:45:17 -0800 (PST) (envelope-from peter@wemm.org) Received: from wemm.org (localhost [127.0.0.1]) by canning.wemm.org (Postfix) with ESMTP id 733AB2A7EA; Fri, 13 Dec 2002 16:45:13 -0800 (PST) (envelope-from peter@wemm.org) X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 To: Julian Elischer Cc: Dan Nelson , Nate Lawson , Kevin Oberman , FreeBSD current users , re@freebsd.org Subject: Re: 5.0 showstopper In-Reply-To: Date: Fri, 13 Dec 2002 16:45:13 -0800 From: Peter Wemm Message-Id: <20021214004513.733AB2A7EA@canning.wemm.org> Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Julian Elischer wrote: > On Fri, 13 Dec 2002, Julian Elischer wrote: > > On Fri, 13 Dec 2002, Dan Nelson wrote: > > > > > In the last episode (Dec 13), Julian Elischer said: > > > > It's always been there. the question is > > > > "Who has broken it?" > > > > I think this is a 5.0 showstopper. Having 5.0 overwrite your > > Windows partition would be "poor" PR. > > Having a quick look at it, it shouldn't be too hard for PHK > > to fix it as he has all the correct parts currently "loaded" > > into his head. Especially such things as making GEOM not allow writes > > to -ve blocknumbers (as must have happenned for root to have been > > overwritten). > > > looking at the code in src/sys/i386/i386/dump_machdep.c, > > we see: > 78 dumplo = di->mediaoffset + di->mediasize - Maxmem * > (off_t)PAGE_SIZE; > 79 dumplo -= sizeof kdh * 2; > 80 i = di->dumper(di->priv, &kdh, 0, dumplo, sizeof kdh); > 81 if (i) > 82 printf("\nDump failed writing header (%d)\n", i); > 83 dumplo += sizeof kdh; > 84 i = 0; > > It looks like the following test should go after line 77 > > if (di->mediasize < ((Maxmem * (off_t)PAGE_SIZE) + > (sizeof kdh * 2) + (16*1024)) { > /* 16K is an arbitrary buffer > * in case the swap part is > * the first part > */ > printf("\nDump failed. Partition too small.\n"); > return; > } We used to force a 64K safety buffer for swapon, and I think we also did 64K for dump before the last MI dump code conversion. I'd feel a little happier if you used 64K here instead of 16K. Cheers, -Peter -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message