Re: [Qemu-devel] [Qemu-ppc] [PATCH 2/2] Add Enhanced Three-Speed Ethernet Controller (eTSEC)

[Fabien Chouteau <chouteau@adacore.com>]

On 07/17/2013 12:22 PM, Alexander Graf wrote:
> 
> On 17.07.2013, at 12:17, Fabien Chouteau wrote:
> 
>> On 07/16/2013 07:50 PM, Scott Wood wrote:
>>> On 07/16/2013 10:28:28 AM, Fabien Chouteau wrote:
>>>> On 07/16/2013 04:06 AM, Scott Wood wrote:
>>>>> On 07/10/2013 12:10:02 PM, Fabien Chouteau wrote:
>>>>>> +    /* ring_base = (etsec->regs[RBASEH].value & 0xF) << 32; */
>>>>>> +    ring_base     += etsec->regs[RBASE0 + ring_nbr].value & ~0x7;
>>>>>> +    start_bd_addr  = bd_addr = etsec->regs[RBPTR0 + ring_nbr].value & ~0x7;
>>>>>
>>>>> What about RBDBPH (upper bits of physical address)?  Likewise for TX.
>>>>>
>>>>
>>>> I'm only interested in 32bits address spaces, so RBASEH, TBASEH, RBDBPH or TBDBPH.
>>>
>>> When adding code to mainline, it's about more than what you're personally interested in...
>>>
>>
>> If I'm not "personally" interested, I will not have time to develop or
>> test a feature. If someone wants to do 36bit addressing, feel free to do
>> it, that's why I send the patch on QEMU-devel, but I won't implement
>> full support of eTSEC myself...
>>
>>> Could you at least have a way to diagnose when the guest OS tries to
>>> use some functionality that you don't support, rather than silently
>>> doing the wrong thing?
>>>
>>
>> This device is so complex, detecting unsupported features would take too
>> much work.
> 
> In this case a simple if(<upper bits of addresses>) hw_error(...) would be good enough :). It's just to make sure that all this valuable knowledge doesn't get lost any someone who eventually does run into 36bit addressing doesn't have to debug for a week to figure out who randomly overwrites his kernel ;).
> 

Since hwaddr is 64bits, I will add RBASEH, TBASEH, RBDBPH and TBDBPH support...

-- 
Fabien Chouteau