Date: Sat, 1 May 1999 07:14:48 +1000 From: Bruce Evans <bde@zeta.org.au> To: dfr@nlsystems.com, klh@us.oracle.com Cc: freebsd-fs@FreeBSD.ORG Subject: Re: When is a FFS not a FFS? Message-ID: <199904302114.HAA19815@godzilla.zeta.org.au>
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>FreeBSD/alpha will mount UFS filesystems from NetBSD/alpha and OSF1 with
>no problems at all. Your problem is that FreeBSD/i386 puts the disklabel
>at a different place on the disk from the alpha OSs. On the alpha, the
>disklabel is stored at offset 64 in block zero but on FreeBSD/i386, it is
>stored at offset zero in block one of the FreeBSD fdisk slice (which can
>be anywhere).
This doesn't explain why `disklabel -r da5' seemed to work, or how
NetBSD/i386 handled labels at a nonstandard offset. I think alpha disks
can only be handled by putting suitable metadata in sectors 0 and 1.
Metadata suitable for NetBSD is not necessarily suitable for FreeBSD.
`disklabel -r' is apparently finding slightly unsuitable metadata.
For FreeBSD, sector 0 should not end with bytes { 0x55, 0xAA }, or else
it will be considered to contain a DOS partition table and you would
have to fudge that right too. Sector 1 must contain a valid label.
A valid label for NetBSD needs more fudging than a valid label for
FreeBSD, since the "raw" partition is 3 ('d') for NetBSD-i386 and 2
('c') for NetBSD-alpha and FreeBSD-any. However, I think NetBSD-i386
labels look like FreeBSD-2.0 labels, and FreeBSD fixes up the latter.
Bruce
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