Date: Sat, 29 Jul 2006 11:47:43 +0200 From: Andreas Klemm <andreas@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: disklabel differences FreeBSD, DragonFly Message-ID: <20060729094743.GA5840@titan.klemm.apsfilter.org> In-Reply-To: <200607282236.k6SMaRlj089446@apollo.backplane.com> References: <20060727063936.GA1246@titan.klemm.apsfilter.org> <20060727122159.GB4217@britannica.bec.de> <20060727202528.GA14954@titan.klemm.apsfilter.org> <200607282236.k6SMaRlj089446@apollo.backplane.com>
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On Fri, Jul 28, 2006 at 03:36:27PM -0700, Matthew Dillon wrote: > :On Thu, Jul 27, 2006 at 02:21:59PM +0200, Joerg Sonnenberger wrote: > :> On Thu, Jul 27, 2006 at 08:39:37AM +0200, Andreas Klemm wrote: > : > :Hmm, for the sake of compatibility, wouldn't it have been an option, > :to add this extra bit to the end of the struct ? > : Andreas /// > > The thing to note here is that FreeBSD had to make room for the > UFS1+UFS2 boot code, so it moved the boot code back to the point > where it abuts the 8-partition-sized disklabel. > > So at least insofar as FreeBSD goes, the partition table cannot be > expanded to 16 partitions with UFS1+UFS2 boot code. I'm guessing > that it *could* be expanded to 16 partitions with UFS1 only or > UFS2 only boot code (assuming the boot code were relocated back > to where it was originally in FreeBSD-4/5 times, before UFS2 came > along). > > With regards to simply recognizing a DragonFly partition... yes, > that would be easy to do. Since FreeBSD is now devfs-based, the > bit we had to steal to support 16 partitions in /dev isn't an issue. Couldn't all BSDs restructure the disklabel in -current so that we would have the same base for the next major release ? Then its only a question of drivers to suppot UFS2 or not. But then compatibility would be there for some time ... Incompatible to UFS's like from Sun I think we are already, so we don't have to honour them. Remember a current thread in german BSD group where somebody complained about FreeBSD - mounting a Sun filesystem r/w - destroyed the filesystem. Luckily he could recover using fsck -b 32. Andreas /// -- Andreas Klemm - Powered by FreeBSD 6 Need a magic printfilter today ? -> http://www.apsfilter.org/
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