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Re: [Xen-devel] [Fwd: Installing from distribution CDs]

I posted a patch on 2/4.  Does anyone have a problem with that patch?


Ian Pratt wrote:

Have we got concensus about how to handle this? (and hence a definitive

Requiring people to change there config command lines is probably OK
provided that we're making it closer to standard Linux behaviour.


-----Original Message-----
From: Anthony Liguori [mailto:anthony@xxxxxxxxxxxxx] Sent: 03 February 2005 02:17
To: Ian Pratt
Cc: Anthony Liguori; Jared Rhine; xen-devel@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] [Fwd: Installing from distribution CDs]

Ian Pratt wrote:

Thanks for looking into this. I wander if it's something to
do with the
way xen packages up the module as an initrd for dom0? Maybe
there's some
difference between an initrd and a ramdisk?

Didn't have time this afternoon but I was able to look into it more this evening and I found the culprit. In arch/i386/kernel/setup.c there was the following line around L1363:


This defaults the root device to /dev/ram0 instead of trying to get it from the boot loader. I'm not sure why this there (perhaps a part of early development?). I've attached a patch that puts back the old_decode_dev call and the behavior becomes exactly what you'd expect: if no root= is specified, initrd still works but if /linuxrc exits you get a VFS error because no root= is specified.

This is what Linux would normally do.

It's very important to note though that applying this patch means that if people had ramdisk=... lines in their configs and didn't have root=/dev/ram0, their machines won't boot anymore.

A solution would be to add an initrd option to the configuration file and have the ramdisk= option default the root device to /dev/ram0.

I've tested this patch on a couple day old copy of xen-unstable. I'm curious to know what the source of this was though because I don't feel very comfortable with just restoring something that was obviously taken out for a reason..

Anthony Liguori

Signed-off-by: Anthony Liguori

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