Date: Sun, 24 Apr 2005 23:49:08 -0700 From: Marcel Moolenaar <marcel@xcllnt.net> To: "M. Warner Losh" <imp@bsdimp.com> Cc: Perforce Change Reviews <perforce@freebsd.org> Subject: Re: PERFORCE change 75921 for review Message-ID: <0ed61916398fb3960649890399e2345b@xcllnt.net> In-Reply-To: <20050425.003757.74682881.imp@bsdimp.com> References: <200504250459.j3P4xWxs057683@repoman.freebsd.org> <20050424.234915.41699183.imp@bsdimp.com> <c228a787d0ab62d16e6c7457b9c5dba5@xcllnt.net> <20050425.003757.74682881.imp@bsdimp.com>
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On Apr 24, 2005, at 11:37 PM, M. Warner Losh wrote: > In message: <c228a787d0ab62d16e6c7457b9c5dba5@xcllnt.net> > Marcel Moolenaar <marcel@xcllnt.net> writes: > : > : On Apr 24, 2005, at 10:49 PM, M. Warner Losh wrote: > : > : > In message: <200504250459.j3P4xWxs057683@repoman.freebsd.org> > : > Marcel Moolenaar <marcel@freebsd.org> writes: > : > : http://perforce.freebsd.org/chv.cgi?CH=75921 > : > : > : > : Change 75921 by marcel@marcel_nfs on 2005/04/25 04:59:01 > : > : > : > : Allow VGA resources across PCI-PCI bridges. Required to > : > : support a PCI based VGA driver with the VGA hardware > : > : behind a PCI-PCI bridge. > : > > : > WE need to make sure that the ISA bit and VGA bits are set > properly on > : > those bridges with vga children and peers of bridges with vga > : > children before allowing this... > : > : Ideally, yes. But since only one PCI device of class display and > : subclass VGA can have the legacy VGA addresses enabled and we're > : not mucking with the system configuration in that respect, we're > : not really doing anything dangerous by allowing the VGA addresses > : without such scrutiny provided we don't try to allocate those > : addresses for any ol' VGA display device that we find on the PCI > : busses in the system. > > Actually yes, really, we need to do this. Most system BIOSes will get > it right, but not all. I think that means we already have problems with syscons(4) then on those machines, right? I mean, syscons just peeks and pokes at the addresses and if it gets something it expects, then there's a VGA device. Allowing VGA addresses across PCI-PCI bridge devices yields exactly the same: some newbusified driver starts to peek and poke at the VGA addresses and if it gets something it expects, then the device can attach. -- Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net
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