Probing of Slots For PCI Busses

The Sun Ultra 250 UPA/PCI system has four PCI plug-in slots, distributed across a single PCI bus. Probing of slots for those busses is controlled by the following two NVRAM configuration variables:

Table G-1 NVRAM Configuration Variables

Variable Name	Default Value	Description
pci0-probe-list	3 ,2, 4, 5	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 876 UltraSCSI bus (internal disks), while devices 2, 4, and 5 are open 33MHz 32-bit slots for plug-in cards.

pci-slot-skip-list is a list (0 to 3) of PCI slots that should not be probed. The values "0" to "3" correspond to the backpanel PCI slots, from bottom to top.

The Ultra 250 systems provide 4 PCI plug-in slots, numbered from 0 to 3, bottom-to-top (accessible and labeled from the back of the system).:

Table G-2 PCI Plug-in Slots

PCI Slot	PCI Bus PCI Device	Width		Speed
3	pci0	/pci@1f,2000/xxx@1	32 bit	33 MHz
2	pci0	/pci@1f,4000/xxx@2	32 bit	33 MHz
1	pci0	/pci@1f,4000/xxx@4	32 bit	33 MHz
0	pci0	/pci@1f,4000/xxx@5	32 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 0 will yield /pci@1f,4000/scsi@5, while plugging an 876 dual-SCSI card into slot 3 will yield two separate "devices" /pci@1f,2000/scsi@1 and /pci@1f,2000/scsi@1,1.