[RFC] Add support for Xen ARM guest on FreeBSD

[Julien Grall]

Hello Nathan,

On 01/17/2014 03:04 AM, Nathan Whitehorn wrote:
> On 01/16/14 18:36, Julien Grall wrote:
>>
>>
>> On 01/16/2014 01:56 AM, Nathan Whitehorn wrote:
>> As I understand, only the simple bus code (see simplebus_attach) is
>> translating the interrupts in the device on a resource.
>> So if you have a node directly attached to the root node with
>> interrupts and MMIO, the driver won't be able to retrieve and
>> translate the interrupts via bus_alloc_resources.

> Why not? nexus on ARM, MIPS, PowerPC, and sparc64 can do this.

I have digged into the code to find the reason of my issue. FreeBSD is 
receiving a VM fault when the driver (xen-dt) is trying to setup the IRQ.

This is because the GIC is not yet initialized but FreeBSD asks to 
unmask the IRQ (sys/arm/arm/gic.c:306).

With this problem, all device nodes that are before the GIC in the 
device tree can't have interrupts. For instance this simple device will 
segfault on FreeBSD:

/ {

   mybus {
      compatible = "simple-bus";

      mynode {
         interrupt-parent = &gic;
         interrupts = <...>;
      };

      gic: gic at xxxx {
         interrupt-controller;
      }
   };
};

The node "mynode" will have to move after the GIC to be able to work 
correctly.

-- 
Julien Grall