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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-04-25 at 13:01 +0100, Julien Grall wrote:
> 
> 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:

With 768M I get a hang.

> 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
> 
> 



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