Message-ID: <486325B8.5010505@sandeen.net>
Date: Thu, 26 Jun 2008 00:14:32 -0500
From: Eric Sandeen <sandeen@sandeen.net>
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Subject: Re: XFS w/ extern journal as root on Linux?
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Mark wrote:
> Well, I tried to convert my non-/home space to XFS with an external journal, but Linux consistently choked on it. I passed "rootfstype=xfs root=/dev/sdb5 rootflags=logdev=/dev/sda2" on the kernel command line (via GRUB) but it panicked every time. 
> 
> Here is a transcript of the boot panic from an unmodified kernel:
> 
> ~~~~~~~~~~~~~~~~~
> md: Autodetecting RAID arrays.
> md: Scanned 0 and added 0 devices.
> md: autorun ...
> md: ... autorun DONE.
> XFS: Invalid device [/dev/sda2], error=-2

Hm, xfs wants to open it by name ("/dev/sda2") but if we look at the
early mount stuff it's doing essentially:

	root_device_name = saved_root_name; /* from root= */

        ROOT_DEV = name_to_dev_t(root_device_name);

        create_dev("/dev/root", ROOT_DEV);
        mount_block_root("/dev/root", root_mountflags);

so it's creating its own dev to open, and this isn't done for the logdev.

I wonder if xfs can do similar tricks, or maybe do name_to_dev_t and do
the open by dev_t not path?

This is probably where somebody tells me I'm wrong for the following
reasons: a, b, c, ... :)

-Eric