Multiple Devices per Host Bridge

In this example system we will have a single socket and one CXL host bridge. There are two CXL memory expanders with 4GB attached to the host bridge.

Things to note:

• Intra-Bridge interleave is not described here.

• The expanders are described by a single CEDT/CFMWS.

• This CEDT/SRAT describes one node for both devices.

• There is only one proximity domain the HMAT for both devices.

CEDT:

           Subtable Type : 00 [CXL Host Bridge Structure]
                Reserved : 00
                  Length : 0020
  Associated host bridge : 00000007
   Specification version : 00000001
                Reserved : 00000000
           Register base : 0000010370400000
         Register length : 0000000000010000

           Subtable Type : 01 [CXL Fixed Memory Window Structure]
                Reserved : 00
                  Length : 002C
                Reserved : 00000000
     Window base address : 0000001000000000
             Window size : 0000000200000000
Interleave Members (2^n) : 00
   Interleave Arithmetic : 00
                Reserved : 0000
             Granularity : 00000000
            Restrictions : 0006
                   QtgId : 0001
            First Target : 00000007

SRAT:

        Subtable Type : 01 [Memory Affinity]
               Length : 28
     Proximity Domain : 00000001
            Reserved1 : 0000
         Base Address : 0000001000000000
       Address Length : 0000000200000000
            Reserved2 : 00000000
Flags (decoded below) : 0000000B
            Enabled : 1
      Hot Pluggable : 1
       Non-Volatile : 0

HMAT:

              Structure Type : 0001 [SLLBI]
                   Data Type : 00   [Latency]
Target Proximity Domain List : 00000000
Target Proximity Domain List : 00000001
                       Entry : 0080
                       Entry : 0100

              Structure Type : 0001 [SLLBI]
                   Data Type : 03   [Bandwidth]
Target Proximity Domain List : 00000000
Target Proximity Domain List : 00000001
                       Entry : 1200
                       Entry : 0200

SLIT:

   Signature : "SLIT"    [System Locality Information Table]
  Localities : 0000000000000003
Locality   0 : 10 20
Locality   1 : FF 0A

DSDT:

Scope (_SB)
{
  Device (S0D0)
  {
      Name (_HID, "ACPI0016" /* Compute Express Link Host Bridge */)  // _HID: Hardware ID
      ...
      Name (_UID, 0x07)  // _UID: Unique ID
  }
  ...
}