Re: [Xen-devel] [PATCH v2 2/8] tools: arm: report an error if the guest RAM is too large

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 25/04/14 12:51, Ian Campbell wrote:
> On Fri, 2014-04-25 at 12:50 +0100, Julien Grall wrote:
>> Hi Ian,
>>
>> On 25/04/14 12:22, Ian Campbell wrote:
>>> Due to the layout of the guest physical address space we cannot support more
>>> than 768M of RAM before overrunning the area set aside for the grant table. 
>>> Due
>>> to the presence of the magic pages at the end of the RAM region guests are
>>> actually limited to 767M.
>>>
>>> Catch this case during domain build and fail gracefully instead of obscurely
>>> later on.
>>>
>>> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
>>> ---
>>> This is the only patch in this series which I consider to be suitable for
>>> backporting to Xen 4.4
>>
>> I agree with you. Without this the guest can crash with weird error.
> 
> I've found that it just hangs silently, which is even more frustrating.

When I try to create a domain with 800M of RAM I get some error from libxl:
libxl: notice: libxl_numa.c:494:libxl__get_numa_candidate: NUMA placement 
failed, performance might be affected
libxl: error: libxl_device.c:934:device_backend_callback: unable to add device 
with path /local/domain/0/backend/vbd/5/51712
libxl: error: libxl_create.c:1062:domcreate_launch_dm: unable to add disk 
devices
libxl: error: libxl_device.c:934:device_backend_callback: unable to remove 
device with path /local/domain/0/backend/vbd/5/51712
libxl: error: libxl.c:1470:devices_destroy_cb: libxl__devices_destroy failed 
for 5


-- 
Julien Grall

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