Sun Microsystems Sun Ultra 450, Руководство пользователя

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UPA Probing
Ultra 450 systems, like all UltraSPARC
TM
systems, are based on the high-speed Ultra
Port Architecture (UPA) bus, a switched system bus that provides up to 32 port ID
addresses (or slots) for high-speed motherboard devices like CPUs, I/O bridges, and
frame buffers. While most Ultra systems employ only three or four active UPA ports,
an Ultra 450 system provides up to nine active ports spread among the following
subsystems.
TABLE 2–1
Active Ports
Device Type UPA Slot Physical Implementation
CPU 0-3 Four plug-in slots
UPA-PCI bridge 4,6,1f Soldered on motherboard
UPA graphics frame buffer 1d, 1e Two plug-in slots
The order of probing these nine port IDs is not subject to user control, however a list
of ports can be excluded from probing via the
upa-port-skip-list
NVRAM
variable. In the following example, the
upa-port-skip-list
variable is used to
exclude one of the UPA-PCI bridges and the primary UPA graphics card from the
UPA probe list.
ok setenv upa-port-skip-list 4,1d
This capability lets you exclude a given device from probing (and subsequent use) by
the system without physically removing the plug-in card. This can be useful in
helping to isolate a failing card in a system experiencing transient failures.
PCI Probing
Of the six PCI buses on the Ultra 450 system , bus 0 (
/pci@1f,4000
in the device
tree) is unique in that it is the only PCI bus that contains motherboard (non plug-in)
devices such as standard Ethernet and SCSI controllers. By definition, these devices
cannot be unplugged and swapped to change the order in which they are probed. To
control the probing order of these devices, the system provides the NVRAM variable
6
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September 1998, Revision A