Re: [Qemu-devel] [PATCH] hw/misc/blob-loader: add a generic blob loader

[Li Guang <lig.fnst@cn.fujitsu.com>]

Peter Crosthwaite wrote:
> On Mon, Jan 6, 2014 at 3:24 PM, Li Guang<lig.fnst@cn.fujitsu.com>  wrote:
>    
>> Li Guang wrote:
>>      
>>> Peter Crosthwaite wrote:
>>>        
>>>> On Mon, Jan 6, 2014 at 2:22 PM, Li Guang<lig.fnst@cn.fujitsu.com>   wrote:
>>>>          
>>>>> Peter Crosthwaite wrote:
>>>>>            
>>>>>> On Mon, Jan 6, 2014 at 1:55 PM, Li Guang<lig.fnst@cn.fujitsu.com>
>>>>>> wrote:
>>>>>>
>>>>>>              
>>>>>>> Li Guang wrote:
>>>>>>>
>>>>>>>                
>>>>>>>> Paolo Bonzini wrote:
>>>>>>>>
>>>>>>>>                  
>>>>>>>>> Il 02/01/2014 11:51, Peter Crosthwaite ha scritto:
>>>>>>>>>
>>>>>>>>>                    
>>>>>>>>>>>> No, please use "realize" and avoid init.  This way you can use an
>>>>>>>>>>>> Error*
>>>>>>>>>>>> to report the error.
>>>>>>>>>>>>
>>>>>>>>>>>> Also, the actual load_image_targphys call probably should be done
>>>>>>>>>>>> in
>>>>>>>>>>>> a
>>>>>>>>>>>> reset handler, not at realize time.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>                          
>>>>>>>>>> Ok I think that settles it. The actual blobbing needs to happen at
>>>>>>>>>> reset time. Perhaps the correct approach is to do as much as
>>>>>>>>>> possible
>>>>>>>>>> (file-path / address sanitsation etc) at realize time, then only
>>>>>>>>>> the
>>>>>>>>>> actual blob load happens at reset. Going on what Paolo said, I
>>>>>>>>>> think
>>>>>>>>>> for this device ::init is actually a nop.
>>>>>>>>>>
>>>>>>>>>>                      
>>>>>>>>> Yeah, also because init is in fact a legacy interface to realize.
>>>>>>>>>
>>>>>>>>> Paolo
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>                    
>>>>>>>> Ok, thanks!
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>                  
>>>>>>> Sorry, seems load blob at reset handler can't do the right job,
>>>>>>> while the same action can play very well at init or realize.
>>>>>>>
>>>>>>>                
>>>>>> What's the exact problem with the reset idea?
>>>>>>
>>>>>>
>>>>>>
>>>>>>              
>>>>> code snippet:
>>>>> static void blob_loader_reset(DeviceState *dev)
>>>>> {
>>>>>       BlobLoaderState *s = BLOB_LOADER(dev);
>>>>>
>>>>>       if (load_image_targphys(s->file, s->hwaddr, MAX_BLOB_SIZE)<   0) {
>>>>>           error_report("can't load %s\n", s->file);
>>>>>           exit(1);
>>>>>       }
>>>>> }
>>>>>
>>>>> if it is device reset handler, no result,
>>>>> kernel doesn't find and parse blob,
>>>>> if it is called at device realize phase,
>>>>> it works.
>>>>>
>>>>>            
>>>> Need to figure out why I think. There's no fundamental problem here
>>>> AFAIK. It must be a bug somewhere.
>>>>
>>>>          
>>>>> Thanks!
>>>>>
>>>>>
>>>>>            
>>>>>>> any suggestion to figure out this problem?
>>>>>>>                
>>>> Run QEMU in GDB and break on your new reset function to see if it is
>>>> ever called. If not have a look into QOM/qdev to see how resets work
>>>> and how that plays with -device args. If yes, have a look into
>>>> load_image_targphys and see why that's not working.
>>>>
>>>>
>>>>          
>>> reset handler definitely be called, and
>>> load_image_targphys has no problem,
>>> I guess it may be impacted by other RAM related codes,
>>> just can't figure out it quickly.
>>>
>>>        
>> Ok, I found the problem finally,
>> load_image_targphys depends on rom_reset to take effect,
>> if it's located at reset handler, rom_reset is called before it,
>> it surely failed to do the right job.
>>
>> so, I have to write my own code to load blob into RAM.
>>
>>      
> dma_memory_write() work?
>
>
>    

what about cpu_physical_memory_write_rom ?

>> Thanks!
>>
>>
>>      
>
>