Re: [BUG] XEN domU crash when PV grub chainloads 32-bit domU grub

[Andreas Sundstrom <sunkan+lists.xen-devel@zappa.cx>]

On 2015-09-23 16:18, Ian Campbell wrote:
> On Wed, 2015-09-23 at 12:47 +0000, Andreas Sundstrom wrote:
>> Citerar Ian Campbell <ian.campbell@citrix.com>:
>>
>>> Along those lines, if the _host_ has buckets of RAM then might it be
>>> worth
>>> restricting it in case the issue is with getting MFNs which are not
>>> representably by the 32-bit PV interfaces? (IIRC the limit is ~160G due
>>> to
>>> the size of the m2p hole, a 32-bit MFN spans 16TB so it's unlikely to
>>> be
>>> that).
>>>
>>> Likewise maybe the issue is with full addresses which don't fit in a 32
>>> -bit
>>> number (which is maybe more likely to happen if grub uses a 1:1 mapping
>>> like I would guess it does), so limiting the host to <4GB might also be
>>> interesting?
>>>
>>
>> If this was meant for me I will need more information to understand  
>> what to test.
>> dom0 has either 12G or 8G memory in my test machines if that makes a  
>> difference.
> 
> It was, sorry for not being clear.
> 
> How much memory do the test machines have?
> 
> If it is more than 160G then try booting with "mem=160G" on the hypervisor
> (not Linux) command line. You can just edit that in via grub.
> 
> Then try with mem=4G (which might require shrinking dom0 too of course).

Well as I said my test machines only have 12 and 8G of memory.
I did a quick test with mem=2G though just to be sure, it failed on
first attempt.

/Andreas