On Wed, 2007-04-11 at 11:40 -0500, Craig Boston wrote: > Looking back at the thread I see that you're porting a Linux driver, > that explains a lot of the confusion. It's been a while since I've > worked with the Linux kernel in depth, but I seem to remember that a lot > of drivers (especially machine-specific ones) would get the resource > directly, e.g. IO port base address, and then do stuff like > > outb(base_addr + offset, value); > value = inb(base_addr + offset); > > or write to mapped memory directly by constructing a pointer to the > address.
Indeed mapped memory is how this is driver is written. > While doing this is possible in FreeBSD, it's discouraged as the > bus_space API tends to make for cleaner code and is also more portable. > On architectures with peculiar alignment requirements, or other > restrictions (DMA buffers having to be below a particular address comes > to mind, or bounce buffers for PAE), the OS will take care of most of > the nitty gritty details for you and allow the driver to contain > higher-level code. Yes bus_space seems much nicer, and very useful I'm sure for platform independence. Cheers, Alan. _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
