Re: [Qemu-devel] [PATCH v2 2/6] qdev: reset qdev along with qdev tree

[Anthony Liguori <aliguori@linux.vnet.ibm.com>]

On 12/16/2010 05:48 PM, Michael S. Tsirkin wrote:
> On Thu, Dec 16, 2010 at 08:31:21PM +0100, Stefan Weil wrote:
>    
>> Am 19.11.2010 10:55, schrieb Isaku Yamahata:
>>      
>>> From: Anthony Liguori<anthony@codemonkey.ws>
>>>
>>> This patch changes the reset handling so that qdev has no knowledge of the
>>> global system reset. Instead, a new bus/device level function is
>>> introduced
>>> that allows all devices/buses on the bus/device to be reset using a depth
>>> first transversal.
>>>
>>> N.B. we have to expose the implicit system bus because we have
>>> various hacks
>>> that result in an implicit system bus existing. Instead, we ought
>>> to have an
>>> explicitly created system bus that we can trigger reset from.
>>> That's a topic
>>> for a future patch though.
>>>
>>> Signed-off-by: Anthony Liguori<aliguori@us.ibm.com>
>>> Signed-off-by: Isaku Yamahata<yamahata@valinux.co.jp>
>>> ---
>>> hw/qdev.c | 28 +++++++++++++++++++---------
>>> hw/qdev.h | 4 ++++
>>> vl.c | 1 +
>>> 3 files changed, 24 insertions(+), 9 deletions(-)
>>>        
>>
>> This patch (which is included in qemu master now) introduces
>> two regressions at least for MIPS system emulation:
>>
>> The emulated MIPS machines mipssim and malta no longer work
>> because qemu tries a null pointer read access (caused by
>> sysbus_get_default returning NULL). Just run any of these
>> machines (big or little endian, 32 or 64 bit) with any mips
>> kernel or bios to get this crash.
>>
>> This first regression can be fixed with a patch which I have
>> sent to qemu-devel.
>>
>> The second regression also occurs with MIPS malta.
>> Networking no longer works with the default pcnet nic.
>>
>> This is caused because the reset function for pcnet is no
>> longer called during system boot. The result in an invalid
>> mac address (all zero) and a non-working nic.
>>
>> For this second regression I still have no simple solution.
>> Of course mips_malta.c should be converted to qdev which
>> would fix both problems (but only for malta system emulation).
>>
>> Maybe other systems / devices don't get their reset functions
>> called during system boot, too.
>>
>> Stefan Weil
>>      
> Ugh, I keep forgetting about the non-qdev systems.
> Maybe it's a good way to finally make everyone to convert? If a system
> maintainer can't be bothered to convert to qdev we can declare the
> system unsupported :)
>    

Honestly, I think that's a fair thing to do.

Regards,

Anthony Liguori