> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > On Behalf Of Marc Jones > Sent: Monday, November 10, 2008 3:28 PM > To: Coreboot > Subject: Re: [coreboot] Resource allocation > > ----- Original Message ---- > > From: Myles Watson <[EMAIL PROTECTED]> > > To: Coreboot <[email protected]> > > Sent: Monday, November 10, 2008 2:53:57 PM > > Subject: [coreboot] Resource allocation > > > > I need to clear up my understanding of resource allocation. Here's my > > understanding of it: > > > > 1. Start at the root with 2 resources (1 for memory, 1 for IO) > > 2. For each child of each link: > > A. Add resources > > B. Get common constraints > > C. Descend links > > D. Propagate back to root > > > > When you're done you should have the Root device with the superset of > all > > devices' resources. > > > > Yes, and each bridge needs the resources grouped which is why the > links(bridges) are desended as found. > > > My question is if resources ever split. In other words, lets imagine a > > device which implements several IO ports in the 0x3fX range and larger > > regions that must be mapped above 0x1000. Since the limit for the > smaller > > regions is 0x7ff and the alignment for the larger regions is 0x1000, > they > > both can't coexist. > > > > What happens? > > Everything > below 0x1000 is legacy IO space and are not typically used by PCI > devices (some devices/firmware sneek some stuff in around 0x800 for > ACPI). As you noted there are some devices that might need to decode > legacy regions to boot. If that is the case they will usually have a > legacy enable bit in the header. In legacy mode the PCI BARs are > ignored. The firmware, option ROM, and driver need to be aware of which > mode it is in. An example is the AMD sb600 IDE controller(Device 20, > Function 1). There is a legacy/PCI mode in the revision register ot > offset 0x8.
Thanks Marc. All right. So the legacy IO resources shouldn't be grouped with the others. Should they be marked Subtractive? Are they declared to be special in a different way? Thanks, Myles -- coreboot mailing list: [email protected] http://www.coreboot.org/mailman/listinfo/coreboot
