On Thursday, March 22, 2012 3:57:11 pm Eric Saint-Etienne wrote: > > If your kernel module creates a device in /dev that implements the > > mmap method, then you don't need to worry about mucking around with > > vm_maps and objects and whatnot. Your mmap method just needs to be > > able to convert offsets into the device into physical memory > > addresses, > > Yes I'm aware of this facility, thank you. > > > and the vm infrastructure will do the rest for you. > > Since this mapping is on the main path of the driver, I'm worried that > the overhead on each access of a page fault and a function call (the > pager associated with a cdev mmap) is too much to bear.
It only does this on the first page fault though, not every access to the page. This can be a bit of a downfall as well as you can't easily invalidate a mapping once you've established it. -- John Baldwin _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
