xref: /linux/Documentation/driver-api/cxl/platform/acpi/hmat.rst (revision e9ef810dfee7a2227da9d423aecb0ced35faddbe)
1.. SPDX-License-Identifier: GPL-2.0
2
3===========================================
4HMAT - Heterogeneous Memory Attribute Table
5===========================================
6
7The Heterogeneous Memory Attributes Table contains information such as cache
8attributes and bandwidth and latency details for memory proximity domains.
9For the purpose of this document, we will only discuss the SSLIB entry.
10
11SLLBI
12=====
13The System Locality Latency and Bandwidth Information records latency and
14bandwidth information for proximity domains.
15
16This table is used by Linux to configure interleave weights and memory tiers.
17
18Example (Heavily truncated for brevity) ::
19
20               Structure Type : 0001 [SLLBI]
21                    Data Type : 00         <- Latency
22 Target Proximity Domain List : 00000000
23 Target Proximity Domain List : 00000001
24                        Entry : 0080       <- DRAM LTC
25                        Entry : 0100       <- CXL LTC
26
27               Structure Type : 0001 [SLLBI]
28                    Data Type : 03         <- Bandwidth
29 Target Proximity Domain List : 00000000
30 Target Proximity Domain List : 00000001
31                        Entry : 1200       <- DRAM BW
32                        Entry : 0200       <- CXL BW
33