How can I fake a device ?

[Iasen Kostov]

takawata at jp.freebsd.org wrote:

>In message <41257789.70508 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.
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 :)

    regards