diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 875c3f39d1..8205d63a4e 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -16,7 +16,7 @@ jobs:
   # Run cargo fmt --check, includes macros/
   style:
     name: style
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -41,7 +41,7 @@ jobs:
   # Compilation check
   check:
     name: check
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       matrix:
         target:
@@ -77,7 +77,7 @@ jobs:
   # Clippy
   clippy:
     name: Cargo clippy
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -104,7 +104,7 @@ jobs:
   # Verify all examples, checks
   checkexamples:
     name: checkexamples
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       matrix:
         target:
@@ -137,7 +137,7 @@ jobs:
   # Verify the example output with run-pass tests
   testexamples:
     name: testexamples
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       matrix:
         target:
@@ -182,7 +182,7 @@ jobs:
   # Check the correctness of macros/ crate
   checkmacros:
     name: checkmacros
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       matrix:
         target:
@@ -216,7 +216,7 @@ jobs:
   # Run the  macros test-suite
   testmacros:
     name: testmacros
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -244,7 +244,7 @@ jobs:
   # Run test suite
   tests:
     name: tests
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -271,7 +271,7 @@ jobs:
   # Build documentation, check links
   docs:
     name: docs
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -318,7 +318,7 @@ jobs:
   # Build the books
   mdbook:
     name: mdbook
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -367,7 +367,7 @@ jobs:
   # This needs to run before book is built
   mergetostablebranch:
     name: If CI passes, merge master branch into release/vX
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     needs:
       - style
       - check
@@ -408,7 +408,7 @@ jobs:
   # If all tests pass, then deploy stage is run
   deploy:
     name: deploy
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     needs:
       mergetostablebranch
 
@@ -561,7 +561,7 @@ jobs:
       - tests
       - docs
       - mdbook
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Mark the job as a success
         run: exit 0
diff --git a/Cargo.toml b/Cargo.toml
index 922385c943..61f8e56eb2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -70,3 +70,10 @@ overflow-checks = false
 
 [patch.crates-io]
 lm3s6965 = { git = "https://github.com/japaric/lm3s6965" }
+
+[features]
+test-critical-section = ["cortex-m/critical-section-single-core"]
+
+[[example]]
+name = "pool"
+required-features = ["test-critical-section"]
diff --git a/book/en/src/preface.md b/book/en/src/preface.md
index f833213ed4..6041dfedea 100644
--- a/book/en/src/preface.md
+++ b/book/en/src/preface.md
@@ -21,6 +21,18 @@ This is the documentation of v1.0.x of RTIC; for the documentation of version
 * v0.5.x go [here](/0.5).
 * v0.4.x go [here](/0.4).
 
+## Is RTIC an RTOS?
+
+A common question is whether RTIC is an RTOS or not, and depending on your background the
+answer may vary. From RTIC's developers point of view; RTIC is a hardware accelerated
+RTOS that utilizes the NVIC in Cortex-M MCUs to perform scheduling, rather than the more
+classical software kernel.
+
+Another common view from the community is that RTIC is a concurrency framework as there
+is no software kernel and that it relies on external HALs.
+
+---
+
 {{#include ../../../README.md:7:47}}
 
 {{#include ../../../README.md:48:}}
diff --git a/macros/src/check.rs b/macros/src/check.rs
index 374fcedd09..b0ad6f8715 100644
--- a/macros/src/check.rs
+++ b/macros/src/check.rs
@@ -53,7 +53,7 @@ pub fn app(app: &App, _analysis: &Analysis) -> parse::Result<Extra> {
 
         // If not enough tasks and first still is None, may cause
         // "custom attribute panicked" due to unwrap on None
-        return Err(parse::Error::new(first.unwrap().span(), &s));
+        return Err(parse::Error::new(first.unwrap().span(), s));
     }
 
     // Check that all exceptions are valid; only exceptions with configurable priorities are
diff --git a/macros/src/codegen/shared_resources.rs b/macros/src/codegen/shared_resources.rs
index 4a75007075..b5dff09da1 100644
--- a/macros/src/codegen/shared_resources.rs
+++ b/macros/src/codegen/shared_resources.rs
@@ -147,6 +147,7 @@ pub fn codegen(
             None
         }
     })) {
+        #[allow(clippy::or_fun_call)]
         let v = prio_to_masks.entry(priority - 1).or_insert(Vec::new());
         v.push(quote!(#device::Interrupt::#name as u32));
         mask_ids.push(quote!(#device::Interrupt::#name as u32));
diff --git a/xtask/src/command.rs b/xtask/src/command.rs
index 2f719bf5c9..100888c075 100644
--- a/xtask/src/command.rs
+++ b/xtask/src/command.rs
@@ -46,7 +46,15 @@ impl<'a> CargoCommand<'a> {
                 features,
                 mode,
             } => {
-                let mut args = vec![self.name(), "--example", example, "--target", target];
+                let mut args = vec![
+                    self.name(),
+                    "--example",
+                    example,
+                    "--target",
+                    target,
+                    "--features",
+                    "test-critical-section",
+                ];
 
                 if let Some(feature_name) = features {
                     args.extend_from_slice(&["--features", feature_name]);