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Re: [Xen-users] run X on dom0 on Hikey board got alignment fault

On Mon, May 16, 2016 at 3:58 AM Julien Grall <julien.grall@xxxxxxx> wrote:
(CC Stefano)

On 13/05/16 01:44, Chenxiao Zhao wrote:
> Hi,


> I have got GPU driver working on dom0 on my Hikey board. When I run
> startx in console, it terminated with bus error by signal 7.
> I traced the kernel and found there is an unhandled fault when X try to
> access a memory mapped address.

Memory mapped address to which physical address? Does this address
belong to a device? If so which one?
From my understanding, it is should be a ram address shared by graphic accelerator and frame buffer display, not belonging to a device. So the graphic accelerator could draw on this memory and displayed by frame buffer device.

> Kernel log:
> Unhandled fault: alignment fault (0x92000061) at 0x0000007f94aac004
> The address should be 4 bytes aligned. The X works well when I boot the
> same kernel without XEN. so I do not think this is caused by X codes.
> What did I miss?
> Anyone can advise the reason causes this issue and how I can fix it?

The first idea that come to my mind is the memory is mapped as device by
Xen whilst Linux maps as normal. Because of stage-2/stage-1 memory
combination, the memory would be mapped as device and therefore all
access should be aligned.

I would recommend you to track down where exactly X is trying to access
(device, RAM...).

Ok, Thanks for your advices. I'll let you know if I had any progress.


Julien Grall
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