xref: /linux/Documentation/driver-api/cxl/platform/acpi/hmat.rst (revision e9ef810dfee7a2227da9d423aecb0ced35faddbe)
1*d1ba3646SGregory Price.. SPDX-License-Identifier: GPL-2.0
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4*d1ba3646SGregory PriceHMAT - Heterogeneous Memory Attribute Table
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6*d1ba3646SGregory Price
7*d1ba3646SGregory PriceThe Heterogeneous Memory Attributes Table contains information such as cache
8*d1ba3646SGregory Priceattributes and bandwidth and latency details for memory proximity domains.
9*d1ba3646SGregory PriceFor the purpose of this document, we will only discuss the SSLIB entry.
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11*d1ba3646SGregory PriceSLLBI
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13*d1ba3646SGregory PriceThe System Locality Latency and Bandwidth Information records latency and
14*d1ba3646SGregory Pricebandwidth information for proximity domains.
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16*d1ba3646SGregory PriceThis table is used by Linux to configure interleave weights and memory tiers.
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18*d1ba3646SGregory PriceExample (Heavily truncated for brevity) ::
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20*d1ba3646SGregory Price               Structure Type : 0001 [SLLBI]
21*d1ba3646SGregory Price                    Data Type : 00         <- Latency
22*d1ba3646SGregory Price Target Proximity Domain List : 00000000
23*d1ba3646SGregory Price Target Proximity Domain List : 00000001
24*d1ba3646SGregory Price                        Entry : 0080       <- DRAM LTC
25*d1ba3646SGregory Price                        Entry : 0100       <- CXL LTC
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27*d1ba3646SGregory Price               Structure Type : 0001 [SLLBI]
28*d1ba3646SGregory Price                    Data Type : 03         <- Bandwidth
29*d1ba3646SGregory Price Target Proximity Domain List : 00000000
30*d1ba3646SGregory Price Target Proximity Domain List : 00000001
31*d1ba3646SGregory Price                        Entry : 1200       <- DRAM BW
32*d1ba3646SGregory Price                        Entry : 0200       <- CXL BW
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