Re: [Qemu-ppc] [PATCH 1/5] target-ppc: Extend rtas-blob

[Alexander Graf]

On 28.08.14 20:20, Aravinda Prasad wrote:
> 
> 
> On Thursday 28 August 2014 04:10 PM, Alexander Graf wrote:
>>
>>
>> On 25.08.14 15:45, Aravinda Prasad wrote:
>>> Extend rtas-blob to accommodate error log. Error log
>>> structure is saved in rtas space upon a machine check
>>> exception.
>>>
>>> Signed-off-by: Aravinda Prasad <address@hidden>
>>
>> I can't say I'm a big fan of this patch. Can we somehow separate that
>> NMI page from the RTAS blob? Also I'd definitely prefer if we keep
>> rtas_entry == rtas_addr - if nothing else for the sake of backwards
>> compatibility.
>>
>> So how about we lay out the structure in memory like this:
>>
>>   [ spapr-rtas.bin ]
>>   [ padding to 4k boundary or whatever sPAPR requires ]
>>   [ 4k NMI region ]
>>
>> Then the only thing we'd have to really change internally is the size
>> information of the rtas blob.
> 
> Either we can have it like this or completely eliminate spapr-rtas.bin
> (and spapr-rtas.S) by simply allocating required space in QEMU and then
> patching the 5 instructions at rtas-entry as earlier discussed with David.
> 
> http://lists.nongnu.org/archive/html/qemu-ppc/2014-08/msg00251.html
> 

I strongly disagree with David. Legally there is no difference between a
.bin file that contains code and an array made of instructions. And the
more target code we can keep outside of QEMU the better.


Alex