Re: [Fwd: Installing from distribution CDs]

[Anthony Liguori <aliguori@us.ibm.com>]

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

Regards,

Ian Pratt wrote:

>Have we got concensus about how to handle this? (and hence a definitive
>patch).
>
>Requiring people to change there config command lines is probably OK
>provided that we're making it closer to standard Linux behaviour.
>
>Ian
>
>  
>
>>-----Original Message-----
>>From: Anthony Liguori [mailto:anthony@codemonkey.ws] 
>>Sent: 03 February 2005 02:17
>>To: Ian Pratt
>>Cc: Anthony Liguori; Jared Rhine; xen-devel@lists.sourceforge.net
>>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:
>>
>>        ROOT_DEV = MKDEV(RAMDISK_MAJOR,0); 
>>/*old_decode_dev(ORIG_ROOT_DEV);*/
>>
>>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..
>>
>>Regards,
>>Anthony Liguori
>>
>>Signed-off-by: Anthony Liguori
>>
>>    
>>
>
>  
>



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