Add initial DRS scheduler placeholder

* Start hacking in cordyceps

This adds a third kind of runqueue, for now it should work the same as the
current "atomics" runqueue, but uses a cordyceps TransferStack instead of
the existing home-rolled linked list.

* Clean up, use new cordyceps feature

* A bit more cleanup

* Update docs to be more clear

1 files changed, 9 insertions, 0 deletions

diff --git a/embassy-executor/Cargo.toml b/embassy-executor/Cargo.toml
index 41636a26f..1cd732dfa 100644
--- a/embassy-executor/Cargo.toml
+++ b/embassy-executor/Cargo.toml
@@ -76,6 +76,12 @@ js-sys = { version = "0.3", optional = true }
 # arch-avr dependencies
 avr-device = { version = "0.7.0", optional = true }
 
+[dependencies.cordyceps]
+version = "0.3"
+git = "https://github.com/hawkw/mycelium"
+rev = "aaad19480d175bfc290f1d4dc2d435c6eb3d9fc5"
+optional = true
+
 [dev-dependencies]
 critical-section = { version = "1.1", features = ["std"] }
 trybuild = "1.0"
@@ -125,3 +131,6 @@ trace = ["_any_trace"]
 ## Enable support for rtos-trace framework
 rtos-trace = ["_any_trace", "metadata-name", "dep:rtos-trace", "dep:embassy-time-driver"]
 _any_trace = []
+
+## Enable "Deadline Rank Scheduler"
+drs-scheduler = ["dep:cordyceps"]