1What:		/sys/firmware/sgi_uv/
2Date:		September 2020
3Contact:	Justin Ernst <justin.ernst@hpe.com>
4Description:
5		The /sys/firmware/sgi_uv directory contains information
6		about the UV platform.
7
8		Under that directory are a number of read-only attributes::
9
10			archtype
11			hub_type
12			hubless
13			partition_id
14			coherence_id
15			uv_type
16
17		The archtype entry contains the UV architecture type that
18		is used to select arch-dependent addresses and features.
19		It can be set via the OEM_ID in the ACPI MADT table or by
20		UVsystab entry both passed from UV BIOS.
21
22		The hub_type entry is used to select the type of hub which is
23		similar to uv_type but encoded in a binary format.  Include
24		the file uv_hub.h to get the definitions.
25
26		The hubless entry basically is present and set only if there
27		is no hub.  In this case the hub_type entry is not present.
28
29		The partition_id entry contains the partition id.
30		UV systems can be partitioned into multiple physical
31		machines, which each partition running a unique copy
32		of the operating system. Each partition will have a unique
33		partition id.
34
35		The coherence_id entry contains the coherence id.
36		A partitioned UV system can have one or more coherence
37		domains. The coherence id indicates which coherence domain
38		this partition is in.
39
40		The uv_type entry contains the hub revision number.
41		This value can be used to identify the UV system version::
42
43			"0.*" = Hubless UV ('*' is subtype)
44			"3.0" = UV2
45			"5.0" = UV3
46			"7.0" = UV4
47			"7.1" = UV4a
48			"9.0" = UV5
49
50		The /sys/firmware/sgi_uv directory also contains two directories::
51
52			hubs/
53			pcibuses/
54
55		The hubs directory contains a number of hub objects, each representing
56		a UV Hub visible to the BIOS. Each hub object's name is appended by a
57		unique ordinal value (ex. /sys/firmware/sgi_uv/hubs/hub_5)
58
59		Each hub object directory contains a number of read-only attributes::
60
61			cnode
62			location
63			name
64			nasid
65			shared
66			this_partition
67
68		The cnode entry contains the cnode number of the corresponding hub.
69		If a cnode value is not applicable, the value returned will be -1.
70
71		The location entry contains the location string of the corresponding hub.
72		This value is used to physically identify a hub within a system.
73
74		The name entry contains the name of the corresponding hub. This name can
75		be two variants::
76
77			"UVHub x.x" = A 'node' ASIC, connecting a CPU to the interconnect
78			fabric. The 'x.x' value represents the ASIC revision.
79			(ex. 'UVHub 5.0')
80
81			"NLxRouter" = A 'router ASIC, only connecting other ASICs to
82			the interconnect fabric. The 'x' value representing
83			the fabric technology version. (ex. 'NL8Router')
84
85		The nasid entry contains the nasid number of the corresponding hub.
86		If a nasid value is not applicable, the value returned will be -1.
87
88		The shared entry contains a boolean value describing whether the
89		corresponding hub is shared between system partitions.
90
91		The this_partition entry contains a boolean value describing whether
92		the corresponding hub is local to the current partition.
93
94		Each hub object directory also contains a number of port objects,
95		each representing a fabric port on the corresponding hub.
96		A port object's name is appended by a unique ordinal value
97		(ex. /sys/firmware/sgi_uv/hubs/hub_5/port_3)
98
99		Each port object directory contains a number of read-only attributes::
100
101			conn_hub
102			conn_port
103
104		The conn_hub entry contains a value representing the unique
105		ordinal value of the hub on the other end of the fabric
106		cable plugged into the port. If the port is disconnected,
107		the value returned will be -1.
108
109		The conn_port entry contains a value representing the unique
110		ordinal value of the port on the other end of the fabric cable
111		plugged into the port. If the port is disconnected, the value
112		returned will be -1.
113
114		Ex:
115			A value of '3' is read from:
116				/sys/firmware/sgi_uv/hubs/hub_5/port_3/conn_hub
117
118			and a value of '6' is read from:
119				/sys/firmware/sgi_uv/hubs/hub_5/port_3/conn_port
120
121			representing that this port is connected to:
122				/sys/firmware/sgi_uv/hubs/hub_3/port_6
123
124		The pcibuses directory contains a number of PCI bus objects.
125		Each PCI bus object's name is appended by its PCI bus address.
126		(ex. pcibus_0003:80)
127
128		Each pcibus object has a number of possible read-only attributes::
129
130			type
131			location
132			slot
133			ppb_addr
134			iio_stack
135
136		The type entry contains a value describing the type of IO at
137		the corresponding PCI bus address. Known possible values
138		across all UV versions are::
139
140			BASE IO
141			PCIe IO
142			PCIe SLOT
143			NODE IO
144			Riser
145			PPB
146
147		The location entry contains the location string of the UV Hub
148		of the CPU physically connected to the corresponding PCI bus.
149
150		The slot entry contains the physical slot number of the
151		corresponding PCI bus. This value is used to physically locate
152		PCI cards within a system.
153
154		The ppb_addr entry contains the PCI address string of the
155		bridged PCI bus. This entry is only present when the PCI bus
156		object type is 'PPB'.
157
158		The iio_stack entry contains a value describing the IIO stack
159		number that the corresponding PCI bus object is connected to.
160