RE: [PATCH 3/3] tools/testing/cxl: Document test configurations

[Dan Williams]

Ira Weiny wrote:
> The devices created, their relationship, and intended testing purpose is
> not extremely clear, especially for those unfamiliar with cxl-test.
> 
> Document the purpose of each hierarchy.  Add ASCII art to show the
> relationship of devices.  Group the device declarations together based
> on the hierarchies.
> 
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> ---
>  tools/testing/cxl/test/cxl.c | 75 ++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 73 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> index bf00dc52fe96..bd38a5fb60ae 100644
> --- a/tools/testing/cxl/test/cxl.c
> +++ b/tools/testing/cxl/test/cxl.c
> @@ -23,6 +23,31 @@ static int interleave_arithmetic;
>  #define NR_CXL_PORT_DECODERS 8
>  #define NR_BRIDGES (NR_CXL_HOST_BRIDGES + NR_CXL_SINGLE_HOST + NR_CXL_RCH)
>  
> +/*
> + * Interleave testing
> + *
> + *             +---------------+                            +---------------+
> + *             | host_bridge[0]|                            | host_bridge[1]|
> + *             +-/---------\---+                            +--/---------\--+
> + *             /-           -\                               /-           -\
> + *           /-               -\                           /-               -\
> + *   +-------------+         +-------------+       +-------------+      +-------------+
> + *   |root_port[0] |         |root_port[1] |       |root_port[2] |      |root_port[3] |
> + *   +------|------+         +------|------+       +------|------+      +------|------+
> + *          |                       |                     |                    |
> + *  +-------|-------+       +-------|-------+     +-------|-------+    +-------|-------+
> + *  |switch_uport[0]|       |switch_uport[1]|     |switch_uport[2]|    |switch_uport[3]|
> + *  +---|-------|---+       +---/-------|---+     +---/-------|---+    +---|-------\---+
> + *      |       \              /        \            /        \            /        \
> + * +----|----++--|------++---------++----|----++---------++----|----++----|----++---------+
> + * |switch   ||switch   ||switch   ||switch   ||switch   ||switch   ||switch   ||switch   |
> + * |_dport[0]||_dport[1]||_dport[2]||_dport[3]||_dport[4]||_dport[5]||_dport[6]||_dport[7]|
> + * +----|----++--|------++----|----++----|----++----|----++----|----++----|----++----|----+
> + *      |        |            |          |          |          |          |          |
> + *  +---|--+   +-|----+   +---|--+   +---|--+    +--|---+  +---|--+   +---|--+   +---|--+
> + *  |mem[0]|   |mem[1]|   |mem[2]|   |mem[3]|    |mem[4]|  |mem[5]|   |mem[6]|   |mem[7]|
> + *  +------+   +------+   +------+   +------+    +------+  +------+   +------+   +------+
> + */

Circling back to merge this I realize that the numbering is off. For
example a snippet from "cxl list -BPT -b cxl_test"

    "ports:root3":[
      {
        "port":"port5",
        "host":"cxl_host_bridge.1",
        "depth":1,
        "nr_dports":2,
        "dports":[
          {
            "dport":"cxl_root_port.1",
            "id":1
          },
          {
            "dport":"cxl_root_port.3",
            "id":3
          }
        ],

This is due to the modulo math at setup time. I only noticed this
because I wanted a diagram to refer to when doing some recent
extensions.

I wonder if we could just use "cxl list" to maintain this diagram, or
maybe circle back and use this to keep an image up to date on a web page
somewhere:

https://lore.kernel.org/linux-cxl/cover.1660895649.git.sunfishho12@xxxxxxxxx/