Probing of Slots For PCI Busses

The Sun Ultra 450 UPA/PCI system has ten PCI plug-in slots, distributed across six PCI busses, called pci0 to pci5; probing of slots for those busses is controlled by the following two NVRAM configuration variables:

Table H-1 NVRAM Configuration Variables

Variable Name	Default Value	Description
pcio-probe-list	3 ,2, 4	Controls probe order of plug-in devices under pcio
pci-slot-skip-list	none	Controls skipping of PCI plug-in slots

pci0-probe-list specifies the device probe order on the "B" bus of the 1F PCI Controller. Device 3 is the motherboard 875 UltraSCSI bus (internal disks), device 2 is the motherboard 875 for removeable media and backpanel external connections (two motherboard 875 chips), while device 4 is an open 33MHz 32-bit slot for plug-in cards.

The remaining 5 PCI busses (pci1 to pci5) probe device slots in ascending numerical order, which order cannot be changed.

pci-slot-skip-list is a list (1 to 10) of PCI slots that should not be probed. The values "1" to "10" correspond to the backpanel PCI slots, from bottom to top.

The Ultra 450 systems provide 10 PCI plug-in slots, numbered from 1 to 10, bottom-to-top (accessible and labeled from the back of the system). The 10 PCI slots correspond to the six PCI busses as follows:

Table H-2

PCI Slot	PCI Bus	PCI Device	Width	Speed
10	pci0	/pci@1f,4000/xxx@4	32 Bit	33 MHz
9	pci2	/pci@4,4000/xxx@2	32 Bit	33 MHz
8	pci2	/pci@4,4000/xxx@3	32 Bit	33 MHz
7	pci2	/pci@4,4000/xxx@4	64 Bit	33MHz
6	pci3	/pci@4,2000/xxx@1	64 Bit	66MHz
5	pci1	/pci@1f,2000/xxx@1	64Bit	66MHz
4	pci5	/pci@6,2000/xxx@1	64 Bit	66MHz
3	pci4	/pci@6,4000/xxx@2	64 Bit	33MHz
2	pci4	/pci@6,4000/xxx@3	64 Bit	33MHz
1	pci4	/pci@6,4000/xxx@4	64 Bit	33MHz

where the xxx will correspond to the particular PCI card plugged into that slot. For example, plugging an 875/glm SCSI controller card into slot 8 will yield/pci@4,4000/scsi@3,while plugging an 876 dual-SCSI card into slot 5 will yield two separate "devices" /pci@1f,2000/scsi@1 and /pci@1f,2000/scsi@1,1. Inserting a PCI-to-PCI card (such as used for a PCI bus expansion box, or as used on some multi-function PCI cards like the Sun Swift PCI card) into slot 4 will yield a device name /pci@6,2000/pci@1, and will subsequently have further devices created "underneath" this node, such as /pci@6,2000/pci@1/SUNW,hme@0,1.

Some of these slots are unavailable if certain graphics options are plugged-in. For example, installing the second FFB graphics card will occupy the physical space of PCI slots 10, 9, and 8. Other graphics options may use up the space occupied by PCI slots 10 to 4.