Re: [Qemu-ppc] [Qemu-devel] [PATCH v3 4/4] target-ppc: Handle ibm, nmi-register RTAS call

[Aravinda Prasad]

On Tuesday 11 November 2014 08:49 AM, David Gibson wrote:
> On Thu, Nov 06, 2014 at 03:30:01PM +0530, Aravinda Prasad wrote:
>> On Wednesday 05 November 2014 09:16 PM, Tom Musta wrote:
>>> On 11/5/2014 2:32 AM, Alexander Graf wrote:
>>>> On 05.11.14 08:13, Aravinda Prasad wrote:
> 
> [snip]
>>>>> + /*
>>>>> +  * ori r3,r3,KVMPPC_H_REPORT_MC_ERR. The KVMPPC_H_REPORT_MC_ERR
>>>>> +  * value is patched below
>>>>> +  */
>>>>> +1:       ori     3,3,0
>>>
>>> Why do "li 3,0" followed by "ori 3,3,X"?  Isn't this just "li 3,X" ?  (aka 
>>> "addi 3,0,X")
>>
>> I remember I first tried doing li r3,X but faced some problem (but not
>> able to exactly recall what was the problem) may be due to not familiar
>> with ppc assembly.
> 
> This would be because with the offset to the private hcalls, the
> actual hcall number is 0xf003, which means an li instruction will sign
> extend it incorrectly. So you will need two instructions to load the
> number.
> 

hmm.. ok

-- 
Regards,
Aravinda