On Monday 06 April 2009 1:07:38 pm Ivan Voras wrote: > 2009/4/6 John Baldwin <j...@freebsd.org>: > > On Sunday 05 April 2009 12:23:39 pm Sergey Babkin wrote: > > > Hmm, the problem is we need to be able to write to BARs to size them. Any OS > > needs to be able to do this to know what address space regions are being > > decoded by devices. We can't avoid writing to BARs. > > I have only vague idea what BARs are and if it's the correct diagnosis > in this case, but the fact is that other operating systems (Windows, > Linux tested) work, so either there is a way around it or the original > premise is wrong-ish.
Every OS writes to BARs to size them during boot. It's the defined procedure for sizing them. A BAR is a base address register, and it is how a PCI device gets memory and I/O port resources. OS (or BIOS) writes a starting address into the register to tell the PCI device where a given resource "starts". -- 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"
