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+What: /sys/devices/uncore_iio_x/dieX
+Date: February 2020
+Contact: Alexander Antonov <alexander.antonov@linux.intel.com>
+Description:
+ Each IIO stack (PCIe root port) has its own IIO PMON block, so
+ each dieX file (where X is die number) holds "Segment:Root Bus"
+ for PCIe root port, which can be monitored by that IIO PMON
+ block.
+ For example, on 4-die Xeon platform with up to 6 IIO stacks per
+ die and, therefore, 6 IIO PMON blocks per die, the mapping of
+ IIO PMON block 0 exposes as the following::
+
+ $ ls /sys/devices/uncore_iio_0/die*
+ -r--r--r-- /sys/devices/uncore_iio_0/die0
+ -r--r--r-- /sys/devices/uncore_iio_0/die1
+ -r--r--r-- /sys/devices/uncore_iio_0/die2
+ -r--r--r-- /sys/devices/uncore_iio_0/die3
+
+ $ tail /sys/devices/uncore_iio_0/die*
+ ==> /sys/devices/uncore_iio_0/die0 <==
+ 0000:00
+ ==> /sys/devices/uncore_iio_0/die1 <==
+ 0000:40
+ ==> /sys/devices/uncore_iio_0/die2 <==
+ 0000:80
+ ==> /sys/devices/uncore_iio_0/die3 <==
+ 0000:c0
+
+ Which means::
+
+ IIO PMU 0 on die 0 belongs to PCI RP on bus 0x00, domain 0x0000
+ IIO PMU 0 on die 1 belongs to PCI RP on bus 0x40, domain 0x0000
+ IIO PMU 0 on die 2 belongs to PCI RP on bus 0x80, domain 0x0000
+ IIO PMU 0 on die 3 belongs to PCI RP on bus 0xc0, domain 0x0000
+
+What: /sys/devices/uncore_upi_x/dieX
+Date: March 2022
+Contact: Alexander Antonov <alexander.antonov@linux.intel.com>
+Description:
+ Each /sys/devices/uncore_upi_X/dieY file holds "upi_Z,die_W"
+ value that means UPI link number X on die Y is connected to UPI
+ link Z on die W and this link between sockets can be monitored
+ by UPI PMON block.
+ For example, 4-die Sapphire Rapids platform has the following
+ UPI 0 topology::
+
+ # tail /sys/devices/uncore_upi_0/die*
+ ==> /sys/devices/uncore_upi_0/die0 <==
+ upi_1,die_1
+ ==> /sys/devices/uncore_upi_0/die1 <==
+ upi_0,die_3
+ ==> /sys/devices/uncore_upi_0/die2 <==
+ upi_1,die_3
+ ==> /sys/devices/uncore_upi_0/die3 <==
+ upi_0,die_1
+
+ Which means::
+
+ UPI link 0 on die 0 is connected to UPI link 1 on die 1
+ UPI link 0 on die 1 is connected to UPI link 0 on die 3
+ UPI link 0 on die 2 is connected to UPI link 1 on die 3
+ UPI link 0 on die 3 is connected to UPI link 0 on die 1 \ No newline at end of file