How can I fake a device ?

[Iasen Kostov]

takawata at jp.freebsd.org wrote:

>In message <4125A25E.4050602 at OTEL.net>, Iasen Kostov wrote:
>
>  
>
>>>>  Hi,
>>>>I want to know is there a way to call *_probe (for device driver) with 
>>>>fake (PCI) device that does not exists in the system ?
>>>>First of all a cant find how "struct device" is declared (i've searched 
>>>>even the compile/ dir) and second I think that I'll need to intercept 
>>>>pci_get_vendor and pci_get_device funcs with my own which should detect 
>>>>the fake device and thus will return vandor/device that I need to fake. 
>>>>I realy don't need anything else except _probe ...
>>>>   
>>>>
>>>>        
>>>>
>>>I have never tried such but grimpsed the PCI framework, 
>>>I propose the following, though I don't imagine why you want 
>>>to do so:
>>>
>>>Your driver have to contain DEVICE_IDENTIFY method 
>>>that calls device_add_child to allocate device_t object.
>>>Then you allocate 'struct pci_devinfo' and initialize 
>>>pci_devinfo as you like. And you have to make your 
>>>driver as a module. Then a device object will show up on 
>>>the device tree on your system.
>>>
>>>You may want to have a look at pci_add_children@/sys/dev/pci/pci.c 
>>>
>>> 
>>>
>>>      
>>>
>>I think I was not clear .. .sorry. I ment to lie the driver that some 
>>device (that is not realy plugged in the machine) exists. Doing so I can 
>>check if drivers _probe() func returns "OK"
>>or not and by checking every device from /usr/share/misc/pci_vendors I 
>>could build device<->driver_file database.
>>    
>>
>
>Hmm, do you want to implement docking station or something?
>This is a part of my interest.
>
>  
>
Don't know what you mean whit "docking station". I want to create 
framework for extracting info from every driver which device it can handle.
Then create create conf for devd or kernel_driver_autoloader :) or 
something like that (e.g. windoze .inf database).

>>I've patched a bit /sys/dev/pci/pci.c like this:
>>
>>typedef uintptr_t *pci_fake_read_ivars_t(pcicfgregs *cfg);
>>static pci_fake_read_ivars_t *pci_fake_read_ivars = NULL;
>>
>>int
>>pci_read_ivar(device_t dev, device_t child, int which, uintptr_t *result)
>>{
>>       struct pci_devinfo *dinfo;
>>       pcicfgregs *cfg = NULL;
>>
>>       if(pci_fake_read_ivars && !strcmp("fake0", dev->nameunit)) {
>>           (*pci_fake_read_ivars)(cfg);
>>       } else {
>>           dinfo = device_get_ivars(child);
>>           cfg = &dinfo->cfg;
>>       }
>>
>>And when I load my module it will set pci_fake_read_ivars and will start 
>>to test drivers probe sending devices with nameunit set to "fake0" thus 
>>telling pci_read_ivar() to fake the return values by calling 
>>pci_fake_read_ivars() callback ... I think this is very messy ... I hope 
>>that it will work this way :)
>>    
>>
>
>pci_read_ivar itself will not access real hardware: cache its value and 
>simply use hardware register index as ivar index.
>So it is enough to initialize
>struct pci_devinfo then call device_set_ivar. Rather, there may be problem
> when pci_cfg_save()@sys/dev/pci/pci.c is called.
>  
>
Thank a lot this will realy simplify the work ! :) I won't need to patch 
sys/dev/pci/pci.c this way. Thanks .