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From: karl@aspodata.se
To: gentoo-user@lists.gentoo.org
Subject: Re: [gentoo-user] Fun with mdadm (Software RAID)
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Comments: In-reply-to Alan Mackenzie <acm@muc.de>
   message dated "Fri, 20 Dec 2024 20:19:55 +0000."
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Alan Mackenzie:
> On Fri, Dec 20, 2024 at 18:44:53 +0100, karl@aspodata.se wrote:
...
> > Please tell if you make booting with metadata 1.2 work.
> > I havn't tested that.
> 
> I've just tried it, with metadata 1.2, and it doesn't work.  I got error
> messages at boot up to the effect that the component partitions were
> lacking valid version 0.0 super blocks.
> 
> People without initramfs appear not to be in the sights of the
> maintainers of this software.  They could so easily have made the
> assembly of metadata 1.2 components on the kernel command line work.
> :-(
...

The cmd line handling and auto mounting seems to be handled in files
like (depending of kernel version I guess):
 drivers/md/md-autodetect.c
 init/do_mounts_md.c
you can find the correct file with
find <kernel top dir> -type f -name \*.c | xargs grep MD_AUTODETECT

The problem might be that in format 1.2, the superblock is at 4K from 
start, could format 1.1 (where the superblock is at start) work ?

Regards,
/Karl Hammar