Re: [Xen-devel] [PATCH ARM v6 04/14] mini-os: headers for ARM

[Thomas Leonard <talex5@xxxxxxxxx>]

On 16 July 2014 22:25, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> Hi Thomas,
>
>
> On 16/07/14 12:07, Thomas Leonard wrote:
>>
>> diff --git a/extras/mini-os/include/arm/os.h
>> b/extras/mini-os/include/arm/os.h
>> new file mode 100644
>> index 0000000..6a1cc37
>> --- /dev/null
>> +++ b/extras/mini-os/include/arm/os.h
>> @@ -0,0 +1,216 @@
>> +#ifndef _OS_H_
>> +#define _OS_H_
>> +
>> +#ifndef __ASSEMBLY__
>> +
>> +#include <mini-os/hypervisor.h>
>> +#include <mini-os/types.h>
>> +#include <mini-os/compiler.h>
>> +#include <mini-os/kernel.h>
>> +#include <xen/xen.h>
>> +
>> +void arch_fini(void);
>> +void timer_handler(evtchn_port_t port, struct pt_regs *regs, void *ign);
>> +
>> +extern void *device_tree;
>> +
>> +#define BUG() while(1){asm volatile (".word 0xe7f000f0\n");} /* Undefined
>> instruction; will call our fault handler. */
>
>
> NIT: I would explain that ARM doesn't provide any undefined instruction so
> we use an encoding that is invalid on ARMv7.

I think it does, although I can't find it in the ARMv7 reference at
the moment. But from
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0489c/CIHJIJCA.html
:

"UND pseudo-instruction

Generate an architecturally undefined instruction. An attempt to
execute an undefined instruction causes the Undefined instruction
exception. Architecturally undefined instructions are expected to
remain undefined.

ARM : 0xV7FYYYFY"

(V is the 4 bits that encode for the condition code, Y allows passing
extra data)


> The other part of this patch looks good to me.
>
> FWIW: Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
>
> Regards,
>
> --
> Julien Grall



-- 
Dr Thomas Leonard        http://0install.net/
GPG: 9242 9807 C985 3C07 44A6  8B9A AE07 8280 59A5 3CC1
GPG: DA98 25AE CAD0 8975 7CDA  BD8E 0713 3F96 CA74 D8BA

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