kern/99979: Get Ready for Kernel Module in C++

John Baldwin jhb at
Tue Jul 11 20:18:30 UTC 2006

On Tuesday 11 July 2006 15:21, mag at wrote:
> John Baldwin wrote:
> > On Tuesday 11 July 2006 12:33, M. Warner Losh wrote:
> >> In message: <200607111115.59844.jhb at>
> >>             John Baldwin <jhb at> writes:
> >> : and OS X both of which I've written a PCI driver for) we require device 
> >> : driver writers to go through a lot more hoops to do certain things like 
> >> : allocate resources.  At the very least there is much that can be 
> > in 
> >> : our driver model.
> >> 
> >> bus_alloc_resources goes a long ways in this respect.
> > 
> > Yes, but in OS X I didn't even have to do that.  All I had to do was ask 
it to 
> > map a BAR if I wanted to use it.  It already "allocated" all the resources 
> > regardless.  Windows was the same way (though a bit weirder, you get a 
> > message that lists all your resources and you have to map them if you want 
> > use them).
> > 
> > -- 
> > John Baldwin
> Do you mean that the kernel pre-allocate resources for all devices whether
> a device has been attached by a device driver?
> Does BIOS do the same thing before OS boots?

Maybe (kernel can allocate it once probe has succeeded perhaps, or just always 
do it) and Yes (if PNP OS is set to No, that is what PNP OS means, is if the 
OS is smart enough to alloc the resources on its own).

John Baldwin

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