Re: disklabel cross-platform compatability ideas...

Poul-Henning Kamp <[email protected]> Wed, 20 Mar 2002 08:31:45 +0100
Newsgroups gmane.os.freebsd.devel.platforms
Message-ID <[email protected]>
In message <[email protected]>, Fred Clift 
writes:

>After doing all of my 'normal' fiddling with a new box I attached an
>external disk case with two 9G viking II disks in it.  The alpha box
>replaced an ia32 box as a server in my home, and the disks had ufs
>partitions on them.
>
>Turns you, and most of you probably already know this, that because of
>partition table location differences between alpha and ia32 I couldn't
>mount the disks.  The disk label seemed to be invalid.  It seems like
>there must be more than just me that are affected by this problem.

I'm busy with a project called "GEOM" right now, which will allow
cross-platform recognition of the various disklabel formats (and
more).

Right now, in -current, you can recognized Solaris disklabels on an
all platforms if you use the GEOM kernel option.

I need to rewrite the BSD disklabel and MBR methods to be endian/
bytewidth agnostic, but then other platforms will be able to recognize
those too.

But that is only the first bit of your trouble, next problem is to
read the actual filesystem, which might be of a different byteorder
persuasion than you machine.

NetBSD has added byteorder-agnostism into ufs/ffs but it is a major
obfuscation of the code and it does not yet cover the snapshot code.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
[email protected]         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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