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Message-ID: <20250430001224.1028656-10-gourry@gourry.net>
Date: Tue, 29 Apr 2025 20:12:16 -0400
From: Gregory Price <gourry@...rry.net>
To: linux-cxl@...r.kernel.org
Cc: linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
kernel-team@...a.com,
dave@...olabs.net,
jonathan.cameron@...wei.com,
dave.jiang@...el.com,
alison.schofield@...el.com,
vishal.l.verma@...el.com,
ira.weiny@...el.com,
dan.j.williams@...el.com,
corbet@....net
Subject: [RFC PATCH 09/17] cxl: docs/linux/cxl-driver - add example configurations
Add 4 example configurations:
- single device
- cross-host-bridge interleave
- intra-host-bridge-interleave
- multi-level interleave
Signed-off-by: Gregory Price <gourry@...rry.net>
---
.../driver-api/cxl/linux/cxl-driver.rst | 10 +
.../example-configurations/hb-interleave.rst | 314 ++++++++++++++
.../intra-hb-interleave.rst | 291 +++++++++++++
.../multi-interleave.rst | 401 ++++++++++++++++++
.../example-configurations/single-device.rst | 246 +++++++++++
5 files changed, 1262 insertions(+)
create mode 100644 Documentation/driver-api/cxl/linux/example-configurations/hb-interleave.rst
create mode 100644 Documentation/driver-api/cxl/linux/example-configurations/intra-hb-interleave.rst
create mode 100644 Documentation/driver-api/cxl/linux/example-configurations/multi-interleave.rst
create mode 100644 Documentation/driver-api/cxl/linux/example-configurations/single-device.rst
diff --git a/Documentation/driver-api/cxl/linux/cxl-driver.rst b/Documentation/driver-api/cxl/linux/cxl-driver.rst
index f403804648b1..8d586b85d346 100644
--- a/Documentation/driver-api/cxl/linux/cxl-driver.rst
+++ b/Documentation/driver-api/cxl/linux/cxl-driver.rst
@@ -519,3 +519,13 @@ from HPA to DPA. This is why they must be aware of the entire interleave set.
Linux does not support unbalanced interleave configurations. As a result, all
endpoints in an interleave set must have the same ways and granularity.
+
+Example Configurations
+**********************
+.. toctree::
+ :maxdepth: 1
+
+ example-configurations/single-device.rst
+ example-configurations/hb-interleave.rst
+ example-configurations/intra-hb-interleave.rst
+ example-configurations/multi-interleave.rst
diff --git a/Documentation/driver-api/cxl/linux/example-configurations/hb-interleave.rst b/Documentation/driver-api/cxl/linux/example-configurations/hb-interleave.rst
new file mode 100644
index 000000000000..f071490763a2
--- /dev/null
+++ b/Documentation/driver-api/cxl/linux/example-configurations/hb-interleave.rst
@@ -0,0 +1,314 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============================
+Inter-Host-Bridge Interleave
+============================
+This cxl-cli configuration dump shows the following host configuration:
+
+* A single socket system with one CXL root
+* CXL Root has Four (4) CXL Host Bridges
+* Two CXL Host Bridges have a single CXL Memory Expander Attached
+* The CXL root is configured to interleave across the two host bridges.
+
+This output is generated by :code:`cxl list -v` and describes the relationships
+between objects exposed in :code:`/sys/bus/cxl/devices/`.
+
+::
+
+ [
+ {
+ "bus":"root0",
+ "provider":"ACPI.CXL",
+ "nr_dports":4,
+ "dports":[
+ {
+ "dport":"pci0000:00",
+ "alias":"ACPI0016:01",
+ "id":0
+ },
+ {
+ "dport":"pci0000:a8",
+ "alias":"ACPI0016:02",
+ "id":4
+ },
+ {
+ "dport":"pci0000:2a",
+ "alias":"ACPI0016:03",
+ "id":1
+ },
+ {
+ "dport":"pci0000:d2",
+ "alias":"ACPI0016:00",
+ "id":5
+ }
+ ],
+
+This chunk shows the CXL "bus" (root0) has 4 downstream ports attached to CXL
+Host Bridges. The `Root` can be considered the singular upstream port attached
+to the platform's memory controller - which routes memory requests to it.
+
+The `ports:root0` section lays out how each of these downstream ports are
+configured. If a port is not configured (id's 0 and 1), they are omitted.
+
+::
+
+ "ports:root0":[
+ {
+ "port":"port1",
+ "host":"pci0000:d2",
+ "depth":1,
+ "nr_dports":3,
+ "dports":[
+ {
+ "dport":"0000:d2:01.1",
+ "alias":"device:02",
+ "id":0
+ },
+ {
+ "dport":"0000:d2:01.3",
+ "alias":"device:05",
+ "id":2
+ },
+ {
+ "dport":"0000:d2:07.1",
+ "alias":"device:0d",
+ "id":113
+ }
+ ],
+
+This chunk shows the available downstream ports associated with the CXL Host
+Bridge :code:`port1`. In this case, :code:`port1` has 3 available downstream
+ports: :code:`dport1`, :code:`dport2`, and :code:`dport113`..
+
+::
+
+ "endpoints:port1":[
+ {
+ "endpoint":"endpoint5",
+ "host":"mem0",
+ "parent_dport":"0000:d2:01.1",
+ "depth":2,
+ "memdev":{
+ "memdev":"mem0",
+ "ram_size":137438953472,
+ "serial":0,
+ "numa_node":0,
+ "host":"0000:d3:00.0"
+ },
+ "decoders:endpoint5":[
+ {
+ "decoder":"decoder5.0",
+ "resource":825975898112,
+ "size":274877906944,
+ "interleave_ways":2,
+ "interleave_granularity":256,
+ "region":"region0",
+ "dpa_resource":0,
+ "dpa_size":137438953472,
+ "mode":"ram"
+ }
+ ]
+ }
+ ],
+
+This chunk shows the endpoints attached to the host bridge :code:`port1`.
+
+:code:`endpoint5` contains a single configured decoder :code:`decoder5.0`
+which has the same interleave configuration as :code:`region0` (shown later).
+
+Next we have the decodesr belonging to the host bridge:
+
+::
+
+ "decoders:port1":[
+ {
+ "decoder":"decoder1.0",
+ "resource":825975898112,
+ "size":274877906944,
+ "interleave_ways":1,
+ "region":"region0",
+ "nr_targets":1,
+ "targets":[
+ {
+ "target":"0000:d2:01.1",
+ "alias":"device:02",
+ "position":0,
+ "id":0
+ }
+ ]
+ }
+ ]
+ },
+
+Host Bridge :code:`port1` has a single decoder (:code:`decoder1.0`), whose only
+target is :code:`dport1` - which is attached to :code:`endpoint5`.
+
+The following chunk shows a similar configuration for Host Bridge :code:`port3`,
+the second host bridge with a memory device attached.
+
+::
+
+ {
+ "port":"port3",
+ "host":"pci0000:a8",
+ "depth":1,
+ "nr_dports":1,
+ "dports":[
+ {
+ "dport":"0000:a8:01.1",
+ "alias":"device:c3",
+ "id":0
+ }
+ ],
+ "endpoints:port3":[
+ {
+ "endpoint":"endpoint6",
+ "host":"mem1",
+ "parent_dport":"0000:a8:01.1",
+ "depth":2,
+ "memdev":{
+ "memdev":"mem1",
+ "ram_size":137438953472,
+ "serial":0,
+ "numa_node":0,
+ "host":"0000:a9:00.0"
+ },
+ "decoders:endpoint6":[
+ {
+ "decoder":"decoder6.0",
+ "resource":825975898112,
+ "size":274877906944,
+ "interleave_ways":2,
+ "interleave_granularity":256,
+ "region":"region0",
+ "dpa_resource":0,
+ "dpa_size":137438953472,
+ "mode":"ram"
+ }
+ ]
+ }
+ ],
+ "decoders:port3":[
+ {
+ "decoder":"decoder3.0",
+ "resource":825975898112,
+ "size":274877906944,
+ "interleave_ways":1,
+ "region":"region0",
+ "nr_targets":1,
+ "targets":[
+ {
+ "target":"0000:a8:01.1",
+ "alias":"device:c3",
+ "position":0,
+ "id":0
+ }
+ ]
+ }
+ ]
+ },
+
+
+The next chunk shows the two CXL host bridges without attached endpoints.
+
+::
+
+ {
+ "port":"port2",
+ "host":"pci0000:00",
+ "depth":1,
+ "nr_dports":2,
+ "dports":[
+ {
+ "dport":"0000:00:01.3",
+ "alias":"device:55",
+ "id":2
+ },
+ {
+ "dport":"0000:00:07.1",
+ "alias":"device:5d",
+ "id":113
+ }
+ ]
+ },
+ {
+ "port":"port4",
+ "host":"pci0000:2a",
+ "depth":1,
+ "nr_dports":1,
+ "dports":[
+ {
+ "dport":"0000:2a:01.1",
+ "alias":"device:d0",
+ "id":0
+ }
+ ]
+ }
+ ],
+
+Next we have the `Root Decoders` belonging to :code:`root0`. This root decoder
+applies the interleave across the downstream ports :code:`port1` and
+:code:`port3` - with a granularity of 256 bytes.
+
+This information is generated by the CXL driver reading the ACPI CEDT CMFWS.
+
+::
+
+ "decoders:root0":[
+ {
+ "decoder":"decoder0.0",
+ "resource":825975898112,
+ "size":274877906944,
+ "interleave_ways":2,
+ "interleave_granularity":256,
+ "max_available_extent":0,
+ "volatile_capable":true,
+ "nr_targets":2,
+ "targets":[
+ {
+ "target":"pci0000:a8",
+ "alias":"ACPI0016:02",
+ "position":1,
+ "id":4
+ },
+ {
+ "target":"pci0000:d2",
+ "alias":"ACPI0016:00",
+ "position":0,
+ "id":5
+ }
+ ],
+
+Finally we have the `Memory Region` associated with the `Root Decoder`
+:code:`decoder0.0`. This region describes the overall interleave configuration
+of the interleave set.
+
+::
+
+ "regions:decoder0.0":[
+ {
+ "region":"region0",
+ "resource":825975898112,
+ "size":274877906944,
+ "type":"ram",
+ "interleave_ways":2,
+ "interleave_granularity":256,
+ "decode_state":"commit",
+ "mappings":[
+ {
+ "position":1,
+ "memdev":"mem1",
+ "decoder":"decoder6.0"
+ },
+ {
+ "position":0,
+ "memdev":"mem0",
+ "decoder":"decoder5.0"
+ }
+ ]
+ }
+ ]
+ }
+ ]
+ }
+ ]
diff --git a/Documentation/driver-api/cxl/linux/example-configurations/intra-hb-interleave.rst b/Documentation/driver-api/cxl/linux/example-configurations/intra-hb-interleave.rst
new file mode 100644
index 000000000000..077dfaf8458d
--- /dev/null
+++ b/Documentation/driver-api/cxl/linux/example-configurations/intra-hb-interleave.rst
@@ -0,0 +1,291 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============================
+Intra-Host-Bridge Interleave
+============================
+This cxl-cli configuration dump shows the following host configuration:
+
+* A single socket system with one CXL root
+* CXL Root has Four (4) CXL Host Bridges
+* One (1) CXL Host Bridges has two CXL Memory Expanders Attached
+* The Host bridge decoder is programmed to interleave across the expanders.
+
+This output is generated by :code:`cxl list -v` and describes the relationships
+between objects exposed in :code:`/sys/bus/cxl/devices/`.
+
+::
+
+ [
+ {
+ "bus":"root0",
+ "provider":"ACPI.CXL",
+ "nr_dports":4,
+ "dports":[
+ {
+ "dport":"pci0000:00",
+ "alias":"ACPI0016:01",
+ "id":0
+ },
+ {
+ "dport":"pci0000:a8",
+ "alias":"ACPI0016:02",
+ "id":4
+ },
+ {
+ "dport":"pci0000:2a",
+ "alias":"ACPI0016:03",
+ "id":1
+ },
+ {
+ "dport":"pci0000:d2",
+ "alias":"ACPI0016:00",
+ "id":5
+ }
+ ],
+
+This chunk shows the CXL "bus" (root0) has 4 downstream ports attached to CXL
+Host Bridges. The `Root` can be considered the singular upstream port attached
+to the platform's memory controller - which routes memory requests to it.
+
+The `ports:root0` section lays out how each of these downstream ports are
+configured. If a port is not configured (id's 0 and 1), they are omitted.
+
+::
+
+ "ports:root0":[
+ {
+ "port":"port1",
+ "host":"pci0000:d2",
+ "depth":1,
+ "nr_dports":3,
+ "dports":[
+ {
+ "dport":"0000:d2:01.1",
+ "alias":"device:02",
+ "id":0
+ },
+ {
+ "dport":"0000:d2:01.3",
+ "alias":"device:05",
+ "id":2
+ },
+ {
+ "dport":"0000:d2:07.1",
+ "alias":"device:0d",
+ "id":113
+ }
+ ],
+
+This chunk shows the available downstream ports associated with the CXL Host
+Bridge :code:`port1`. In this case, :code:`port1` has 3 available downstream
+ports: :code:`dport1`, :code:`dport2`, and :code:`dport113`..
+
+::
+
+ "endpoints:port1":[
+ {
+ "endpoint":"endpoint5",
+ "host":"mem0",
+ "parent_dport":"0000:d2:01.1",
+ "depth":2,
+ "memdev":{
+ "memdev":"mem0",
+ "ram_size":137438953472,
+ "serial":0,
+ "numa_node":0,
+ "host":"0000:d3:00.0"
+ },
+ "decoders:endpoint5":[
+ {
+ "decoder":"decoder5.0",
+ "resource":825975898112,
+ "size":274877906944,
+ "interleave_ways":2,
+ "interleave_granularity":256,
+ "region":"region0",
+ "dpa_resource":0,
+ "dpa_size":137438953472,
+ "mode":"ram"
+ }
+ ]
+ },
+ {
+ "endpoint":"endpoint6",
+ "host":"mem1",
+ "parent_dport":"0000:d2:01.3,
+ "depth":2,
+ "memdev":{
+ "memdev":"mem1",
+ "ram_size":137438953472,
+ "serial":0,
+ "numa_node":0,
+ "host":"0000:a9:00.0"
+ },
+ "decoders:endpoint6":[
+ {
+ "decoder":"decoder6.0",
+ "resource":825975898112,
+ "size":274877906944,
+ "interleave_ways":2,
+ "interleave_granularity":256,
+ "region":"region0",
+ "dpa_resource":0,
+ "dpa_size":137438953472,
+ "mode":"ram"
+ }
+ ]
+ }
+ ],
+
+This chunk shows the endpoints attached to the host bridge :code:`port1`.
+
+:code:`endpoint5` contains a single configured decoder :code:`decoder5.0`
+which has the same interleave configuration memory region they belong to
+(show later).
+
+Next we have the decoders belonging to the host bridge:
+
+::
+
+ "decoders:port1":[
+ {
+ "decoder":"decoder1.0",
+ "resource":825975898112,
+ "size":274877906944,
+ "interleave_ways":2,
+ "interleave_granularity":256,
+ "region":"region0",
+ "nr_targets":2,
+ "targets":[
+ {
+ "target":"0000:d2:01.1",
+ "alias":"device:02",
+ "position":0,
+ "id":0
+ },
+ {
+ "target":"0000:d2:01.3",
+ "alias":"device:05",
+ "position":1,
+ "id":0
+ }
+ ]
+ }
+ ]
+ },
+
+Host Bridge :code:`port1` has a single decoder (:code:`decoder1.0`) with two
+targets: :code:`dport1` and :code:`dport3` - which are attached to
+:code:`endpoint5` and :code:`endpoint6` respectively.
+
+The host bridge decoder interleaves these devices at a 256 byte granularity.
+
+The next chunk shows the three CXL host bridges without attached endpoints.
+
+::
+
+ {
+ "port":"port2",
+ "host":"pci0000:00",
+ "depth":1,
+ "nr_dports":2,
+ "dports":[
+ {
+ "dport":"0000:00:01.3",
+ "alias":"device:55",
+ "id":2
+ },
+ {
+ "dport":"0000:00:07.1",
+ "alias":"device:5d",
+ "id":113
+ }
+ ]
+ },
+ {
+ "port":"port3",
+ "host":"pci0000:a8",
+ "depth":1,
+ "nr_dports":1,
+ "dports":[
+ {
+ "dport":"0000:a8:01.1",
+ "alias":"device:c3",
+ "id":0
+ }
+ ],
+ },
+ {
+ "port":"port4",
+ "host":"pci0000:2a",
+ "depth":1,
+ "nr_dports":1,
+ "dports":[
+ {
+ "dport":"0000:2a:01.1",
+ "alias":"device:d0",
+ "id":0
+ }
+ ]
+ }
+ ],
+
+Next we have the `Root Decoders` belonging to :code:`root0`. This root decoder
+applies the interleave across the downstream ports :code:`port1` and
+:code:`port3` - with a granularity of 256 bytes.
+
+This information is generated by the CXL driver reading the ACPI CEDT CMFWS.
+
+::
+
+ "decoders:root0":[
+ {
+ "decoder":"decoder0.0",
+ "resource":825975898112,
+ "size":274877906944,
+ "interleave_ways":1,
+ "max_available_extent":0,
+ "volatile_capable":true,
+ "nr_targets":2,
+ "targets":[
+ {
+ "target":"pci0000:a8",
+ "alias":"ACPI0016:02",
+ "position":1,
+ "id":4
+ },
+ ],
+
+Finally we have the `Memory Region` associated with the `Root Decoder`
+:code:`decoder0.0`. This region describes the overall interleave configuration
+of the interleave set.
+
+::
+
+ "regions:decoder0.0":[
+ {
+ "region":"region0",
+ "resource":825975898112,
+ "size":274877906944,
+ "type":"ram",
+ "interleave_ways":2,
+ "interleave_granularity":256,
+ "decode_state":"commit",
+ "mappings":[
+ {
+ "position":1,
+ "memdev":"mem1",
+ "decoder":"decoder6.0"
+ },
+ {
+ "position":0,
+ "memdev":"mem0",
+ "decoder":"decoder5.0"
+ }
+ ]
+ }
+ ]
+ }
+ ]
+ }
+ ]
diff --git a/Documentation/driver-api/cxl/linux/example-configurations/multi-interleave.rst b/Documentation/driver-api/cxl/linux/example-configurations/multi-interleave.rst
new file mode 100644
index 000000000000..008f9053c630
--- /dev/null
+++ b/Documentation/driver-api/cxl/linux/example-configurations/multi-interleave.rst
@@ -0,0 +1,401 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================
+Multi-Level Interleave
+======================
+This cxl-cli configuration dump shows the following host configuration:
+
+* A single socket system with one CXL root
+* CXL Root has Four (4) CXL Host Bridges
+* Two CXL Host Bridges have a two CXL Memory Expanders Attached each.
+* The CXL root is configured to interleave across the two host bridges.
+* Each host bridge with expanders interleaves across two endpoints.
+
+This output is generated by :code:`cxl list -v` and describes the relationships
+between objects exposed in :code:`/sys/bus/cxl/devices/`.
+
+::
+
+ [
+ {
+ "bus":"root0",
+ "provider":"ACPI.CXL",
+ "nr_dports":4,
+ "dports":[
+ {
+ "dport":"pci0000:00",
+ "alias":"ACPI0016:01",
+ "id":0
+ },
+ {
+ "dport":"pci0000:a8",
+ "alias":"ACPI0016:02",
+ "id":4
+ },
+ {
+ "dport":"pci0000:2a",
+ "alias":"ACPI0016:03",
+ "id":1
+ },
+ {
+ "dport":"pci0000:d2",
+ "alias":"ACPI0016:00",
+ "id":5
+ }
+ ],
+
+This chunk shows the CXL "bus" (root0) has 4 downstream ports attached to CXL
+Host Bridges. The `Root` can be considered the singular upstream port attached
+to the platform's memory controller - which routes memory requests to it.
+
+The `ports:root0` section lays out how each of these downstream ports are
+configured. If a port is not configured (id's 0 and 1), they are omitted.
+
+::
+
+ "ports:root0":[
+ {
+ "port":"port1",
+ "host":"pci0000:d2",
+ "depth":1,
+ "nr_dports":3,
+ "dports":[
+ {
+ "dport":"0000:d2:01.1",
+ "alias":"device:02",
+ "id":0
+ },
+ {
+ "dport":"0000:d2:01.3",
+ "alias":"device:05",
+ "id":2
+ },
+ {
+ "dport":"0000:d2:07.1",
+ "alias":"device:0d",
+ "id":113
+ }
+ ],
+
+This chunk shows the available downstream ports associated with the CXL Host
+Bridge :code:`port1`. In this case, :code:`port1` has 3 available downstream
+ports: :code:`dport0`, :code:`dport2`, and :code:`dport113`.
+
+::
+
+ "endpoints:port1":[
+ {
+ "endpoint":"endpoint5",
+ "host":"mem0",
+ "parent_dport":"0000:d2:01.1",
+ "depth":2,
+ "memdev":{
+ "memdev":"mem0",
+ "ram_size":137438953472,
+ "serial":0,
+ "numa_node":0,
+ "host":"0000:d3:00.0"
+ },
+ "decoders:endpoint5":[
+ {
+ "decoder":"decoder5.0",
+ "resource":825975898112,
+ "size":549755813888,
+ "interleave_ways":4,
+ "interleave_granularity":256,
+ "region":"region0",
+ "dpa_resource":0,
+ "dpa_size":137438953472,
+ "mode":"ram"
+ }
+ ]
+ },
+ {
+ "endpoint":"endpoint6",
+ "host":"mem1",
+ "parent_dport":"0000:d2:01.3",
+ "depth":2,
+ "memdev":{
+ "memdev":"mem1",
+ "ram_size":137438953472,
+ "serial":0,
+ "numa_node":0,
+ "host":"0000:d3:00.0"
+ },
+ "decoders:endpoint6":[
+ {
+ "decoder":"decoder6.0",
+ "resource":825975898112,
+ "size":549755813888,
+ "interleave_ways":4,
+ "interleave_granularity":256,
+ "region":"region0",
+ "dpa_resource":0,
+ "dpa_size":137438953472,
+ "mode":"ram"
+ }
+ ]
+ }
+ ],
+
+This chunk shows the endpoints attached to the host bridge :code:`port1`.
+
+:code:`endpoint5` contains a single configured decoder :code:`decoder5.0`
+which has the same interleave configuration as :code:`region0` (shown later).
+
+:code:`endpoint6` contains a single configured decoder :code:`decoder5.0`
+which has the same interleave configuration as :code:`region0` (shown later).
+
+Next we have the decoders belonging to the host bridge:
+
+::
+
+ "decoders:port1":[
+ {
+ "decoder":"decoder1.0",
+ "resource":825975898112,
+ "size":549755813888,
+ "interleave_ways":2,
+ "interleave_granularity":512,
+ "region":"region0",
+ "nr_targets":2,
+ "targets":[
+ {
+ "target":"0000:d2:01.1",
+ "alias":"device:02",
+ "position":0,
+ "id":0
+ },
+ {
+ "target":"0000:d2:01.3",
+ "alias":"device:05",
+ "position":2,
+ "id":0
+ }
+ ]
+ }
+ ]
+ },
+
+Host Bridge :code:`port1` has a single decoder (:code:`decoder1.0`), whose
+targets are :code:`dport0` and :code:`dport2` - which are attached to
+:code:`endpoint5` and :code:`endpoint6` respectively.
+
+The following chunk shows a similar configuration for Host Bridge :code:`port3`,
+the second host bridge with a memory device attached.
+
+::
+
+ {
+ "port":"port3",
+ "host":"pci0000:a8",
+ "depth":1,
+ "nr_dports":1,
+ "dports":[
+ {
+ "dport":"0000:a8:01.1",
+ "alias":"device:c3",
+ "id":0
+ },
+ {
+ "dport":"0000:a8:01.3",
+ "alias":"device:c5",
+ "id":0
+ }
+ ],
+ "endpoints:port3":[
+ {
+ "endpoint":"endpoint7",
+ "host":"mem2",
+ "parent_dport":"0000:a8:01.1",
+ "depth":2,
+ "memdev":{
+ "memdev":"mem2",
+ "ram_size":137438953472,
+ "serial":0,
+ "numa_node":0,
+ "host":"0000:a9:00.0"
+ },
+ "decoders:endpoint7":[
+ {
+ "decoder":"decoder7.0",
+ "resource":825975898112,
+ "size":549755813888,
+ "interleave_ways":4,
+ "interleave_granularity":256,
+ "region":"region0",
+ "dpa_resource":0,
+ "dpa_size":137438953472,
+ "mode":"ram"
+ }
+ ]
+ },
+ {
+ "endpoint":"endpoint8",
+ "host":"mem3",
+ "parent_dport":"0000:a8:01.3",
+ "depth":2,
+ "memdev":{
+ "memdev":"mem3",
+ "ram_size":137438953472,
+ "serial":0,
+ "numa_node":0,
+ "host":"0000:a9:00.0"
+ },
+ "decoders:endpoint8":[
+ {
+ "decoder":"decoder8.0",
+ "resource":825975898112,
+ "size":549755813888,
+ "interleave_ways":4,
+ "interleave_granularity":256,
+ "region":"region0",
+ "dpa_resource":0,
+ "dpa_size":137438953472,
+ "mode":"ram"
+ }
+ ]
+ }
+ ],
+ "decoders:port3":[
+ {
+ "decoder":"decoder3.0",
+ "resource":825975898112,
+ "size":549755813888,
+ "interleave_ways":2,
+ "interleave_granularity":512,
+ "region":"region0",
+ "nr_targets":1,
+ "targets":[
+ {
+ "target":"0000:a8:01.1",
+ "alias":"device:c3",
+ "position":1,
+ "id":0
+ },
+ {
+ "target":"0000:a8:01.3",
+ "alias":"device:c5",
+ "position":3,
+ "id":0
+ }
+ ]
+ }
+ ]
+ },
+
+
+The next chunk shows the two CXL host bridges without attached endpoints.
+
+::
+
+ {
+ "port":"port2",
+ "host":"pci0000:00",
+ "depth":1,
+ "nr_dports":2,
+ "dports":[
+ {
+ "dport":"0000:00:01.3",
+ "alias":"device:55",
+ "id":2
+ },
+ {
+ "dport":"0000:00:07.1",
+ "alias":"device:5d",
+ "id":113
+ }
+ ]
+ },
+ {
+ "port":"port4",
+ "host":"pci0000:2a",
+ "depth":1,
+ "nr_dports":1,
+ "dports":[
+ {
+ "dport":"0000:2a:01.1",
+ "alias":"device:d0",
+ "id":0
+ }
+ ]
+ }
+ ],
+
+Next we have the `Root Decoders` belonging to :code:`root0`. This root decoder
+applies the interleave across the downstream ports :code:`port1` and
+:code:`port3` - with a granularity of 256 bytes.
+
+This information is generated by the CXL driver reading the ACPI CEDT CMFWS.
+
+::
+
+ "decoders:root0":[
+ {
+ "decoder":"decoder0.0",
+ "resource":825975898112,
+ "size":549755813888,
+ "interleave_ways":2,
+ "interleave_granularity":256,
+ "max_available_extent":0,
+ "volatile_capable":true,
+ "nr_targets":2,
+ "targets":[
+ {
+ "target":"pci0000:a8",
+ "alias":"ACPI0016:02",
+ "position":1,
+ "id":4
+ },
+ {
+ "target":"pci0000:d2",
+ "alias":"ACPI0016:00",
+ "position":0,
+ "id":5
+ }
+ ],
+
+Finally we have the `Memory Region` associated with the `Root Decoder`
+:code:`decoder0.0`. This region describes the overall interleave configuration
+of the interleave set. So we see there are a total of :code:`4` interleave
+targets across 4 endpoint decoders.
+
+::
+
+ "regions:decoder0.0":[
+ {
+ "region":"region0",
+ "resource":825975898112,
+ "size":549755813888,
+ "type":"ram",
+ "interleave_ways":4,
+ "interleave_granularity":256,
+ "decode_state":"commit",
+ "mappings":[
+ {
+ "position":3,
+ "memdev":"mem3",
+ "decoder":"decoder8.0"
+ },
+ {
+ "position":2,
+ "memdev":"mem1",
+ "decoder":"decoder6.0"
+ }
+ {
+ "position":1,
+ "memdev":"mem2",
+ "decoder":"decoder7.0"
+ },
+ {
+ "position":0,
+ "memdev":"mem0",
+ "decoder":"decoder5.0"
+ }
+ ]
+ }
+ ]
+ }
+ ]
+ }
+ ]
diff --git a/Documentation/driver-api/cxl/linux/example-configurations/single-device.rst b/Documentation/driver-api/cxl/linux/example-configurations/single-device.rst
new file mode 100644
index 000000000000..5fd38eb0aaf4
--- /dev/null
+++ b/Documentation/driver-api/cxl/linux/example-configurations/single-device.rst
@@ -0,0 +1,246 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+Single Device
+=============
+This cxl-cli configuration dump shows the following host configuration:
+
+* A single socket system with one CXL root
+* CXL Root has Four (4) CXL Host Bridges
+* One CXL Host Bridges has a single CXL Memory Expander Attached
+* No interleave is present.
+
+This output is generated by :code:`cxl list -v` and describes the relationships
+between objects exposed in :code:`/sys/bus/cxl/devices/`.
+
+::
+
+ [
+ {
+ "bus":"root0",
+ "provider":"ACPI.CXL",
+ "nr_dports":4,
+ "dports":[
+ {
+ "dport":"pci0000:00",
+ "alias":"ACPI0016:01",
+ "id":0
+ },
+ {
+ "dport":"pci0000:a8",
+ "alias":"ACPI0016:02",
+ "id":4
+ },
+ {
+ "dport":"pci0000:2a",
+ "alias":"ACPI0016:03",
+ "id":1
+ },
+ {
+ "dport":"pci0000:d2",
+ "alias":"ACPI0016:00",
+ "id":5
+ }
+ ],
+
+This chunk shows the CXL "bus" (root0) has 4 downstream ports attached to CXL
+Host Bridges. The `Root` can be considered the singular upstream port attached
+to the platform's memory controller - which routes memory requests to it.
+
+The `ports:root0` section lays out how each of these downstream ports are
+configured. If a port is not configured (id's 0, 1, and 4), they are omitted.
+
+::
+
+ "ports:root0":[
+ {
+ "port":"port1",
+ "host":"pci0000:d2",
+ "depth":1,
+ "nr_dports":3,
+ "dports":[
+ {
+ "dport":"0000:d2:01.1",
+ "alias":"device:02",
+ "id":0
+ },
+ {
+ "dport":"0000:d2:01.3",
+ "alias":"device:05",
+ "id":2
+ },
+ {
+ "dport":"0000:d2:07.1",
+ "alias":"device:0d",
+ "id":113
+ }
+ ],
+
+This chunk shows the available downstream ports associated with the CXL Host
+Bridge :code:`port1`. In this case, :code:`port1` has 3 available downstream
+ports: :code:`dport1`, :code:`dport2`, and :code:`dport113`..
+
+::
+
+ "endpoints:port1":[
+ {
+ "endpoint":"endpoint5",
+ "host":"mem0",
+ "parent_dport":"0000:d2:01.1",
+ "depth":2,
+ "memdev":{
+ "memdev":"mem0",
+ "ram_size":137438953472,
+ "serial":0,
+ "numa_node":0,
+ "host":"0000:d3:00.0"
+ },
+ "decoders:endpoint5":[
+ {
+ "decoder":"decoder5.0",
+ "resource":825975898112,
+ "size":137438953472,
+ "interleave_ways":1,
+ "region":"region0",
+ "dpa_resource":0,
+ "dpa_size":137438953472,
+ "mode":"ram"
+ }
+ ]
+ }
+ ],
+
+This chunk shows the endpoints attached to the host bridge :code:`port1`.
+
+:code:`endpoint5` contains a single configured decoder :code:`decoder5.0`
+which has the same interleave configuration as :code:`region0` (shown later).
+
+Next we have the decoders belonging to the host bridge:
+
+::
+
+ "decoders:port1":[
+ {
+ "decoder":"decoder1.0",
+ "resource":825975898112,
+ "size":137438953472,
+ "interleave_ways":1,
+ "region":"region0",
+ "nr_targets":1,
+ "targets":[
+ {
+ "target":"0000:d2:01.1",
+ "alias":"device:02",
+ "position":0,
+ "id":0
+ }
+ ]
+ }
+ ]
+ },
+
+Host Bridge :code:`port1` has a single decoder (:code:`decoder1.0`), whose only
+target is :code:`dport1` - which is attached to :code:`endpoint5`.
+
+The next chunk shows the three CXL host bridges without attached endpoints.
+
+::
+
+ {
+ "port":"port2",
+ "host":"pci0000:00",
+ "depth":1,
+ "nr_dports":2,
+ "dports":[
+ {
+ "dport":"0000:00:01.3",
+ "alias":"device:55",
+ "id":2
+ },
+ {
+ "dport":"0000:00:07.1",
+ "alias":"device:5d",
+ "id":113
+ }
+ ]
+ },
+ {
+ "port":"port3",
+ "host":"pci0000:a8",
+ "depth":1,
+ "nr_dports":1,
+ "dports":[
+ {
+ "dport":"0000:a8:01.1",
+ "alias":"device:c3",
+ "id":0
+ }
+ ]
+ },
+ {
+ "port":"port4",
+ "host":"pci0000:2a",
+ "depth":1,
+ "nr_dports":1,
+ "dports":[
+ {
+ "dport":"0000:2a:01.1",
+ "alias":"device:d0",
+ "id":0
+ }
+ ]
+ }
+ ],
+
+Next we have the `Root Decoders` belonging to :code:`root0`. This root decoder
+is a pass-through decoder because :code:`interleave_ways` is set to :code:`1`.
+
+This information is generated by the CXL driver reading the ACPI CEDT CMFWS.
+
+::
+
+ "decoders:root0":[
+ {
+ "decoder":"decoder0.0",
+ "resource":825975898112,
+ "size":137438953472,
+ "interleave_ways":1,
+ "max_available_extent":0,
+ "volatile_capable":true,
+ "nr_targets":1,
+ "targets":[
+ {
+ "target":"pci0000:d2",
+ "alias":"ACPI0016:00",
+ "position":0,
+ "id":5
+ }
+ ],
+
+Finally we have the `Memory Region` associated with the `Root Decoder`
+:code:`decoder0.0`. This region describes the discrete region associated
+with the lone device.
+
+::
+
+ "regions:decoder0.0":[
+ {
+ "region":"region0",
+ "resource":825975898112,
+ "size":137438953472,
+ "type":"ram",
+ "interleave_ways":1,
+ "decode_state":"commit",
+ "mappings":[
+ {
+ "position":0,
+ "memdev":"mem0",
+ "decoder":"decoder5.0"
+ }
+ ]
+ }
+ ]
+ }
+ ]
+ }
+ ]
--
2.49.0
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