[Xen-devel] Re: [Xen-Users] System reboots after "Scrubbing free RAM" Xen 4.0.1 linux 2.6.37-rc3, crash with less than 16 GB of dom0_mem

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Thu, Nov 25, 2010 at 09:06:11AM +0100, Joaquin Fernandez Piqueras wrote:
>
> Al 25/11/10 00:16, En/na Marek Kaszycki ha escrit:
>> Hi Everyone
>>
>> I have sorted out the initial issues I've had and decided to give Xen  
>> another go.
>>
>> I'm trying to run Xen using kernel 2.6.37-rc3 (previous attempt with  
>> rc1 failed, and when I gave it a second go, rc3 was already out).
>>
>> As previously, 2.6.37-rc3 boots fine natively. 2.6.32 boots natively  
>> and under Xen as dom0, but I have reservations against running 2.6.32,  
>> please bear with me.
>> Booting 2.6.37-rc3 under Xen (4.0.1-1, squeeze) causes a reboot right  
>> after "Scrubbing free RAM" appears -- I believe some tables appear  
>> just to blink on the screen right afterwards, but I am unable to  
>> confirm just what exactly is there -- I don't have a serial console  
>> attached -- so I am unable to capture the output from Xen or dom0.
>>
>> I am at a loss as to what causes this. I have compiled the kernel  
>> myself, following the advice on  
>> http://wiki.xen.org/xenwiki/XenParavirtOps
>>
>> Since there are additional lines after the error message, I believe  
>> the hypervisor completes its init and the reboot happens just when the  
>> hypervisor wants to boot dom0.
>>
>> I have checked the threads:
>> http://lists.xensource.com/archives/html/xen-users/2010-11/msg00420.html
>> http://lists.xensource.com/archives/html/xen-devel/2010-04/msg01227.html
>> My system has just 8 GB of RAM and just one CPU. Following the advice,  
>> I have added 'noreboot' to Xen entry in grub.cfg, but even though Xen  
>> doesn't reboot the system now, it's worse because right after  
>> "Scrubbing free RAM", the screen goes blank, no cursor or anything,  
>> and just stays this way.
>>
>> I have uploaded the grub.cfg and kernel .config to the following  
>> locations:
>> http://www.kaszycki.pl/xen/grub.cfg
>> http://www.kaszycki.pl/xen/kconfig
>>
>> Thanks in advance for all your help.
>>
>
> Hi,
>
> I have the same issue with a server with 32GB of RAM. In my case the  
> system reboots after "Scrubbing free RAM" when the dom0_mem parameter is  
> 16GB or less. I don't know if my problem is related , but I  
> workarrounded it setting dom0_mem=17GB and when the system boots I  
> decrease this value to 2GB with the "xm mem-set" command.
>
> It's not the best solution, but really I don't know how to get the  
> "dom0_mem=2GB" work.
>

This sounds like a bug.
What dom0 kernel version were you running?
Can you post the serial log about the crash?

I added xen-devel as CC.

-- Pasi


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