From e7a5ac923c7988e8d899ed3160dba5b5f9cbc0d3 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 03:26:21 +0200
Subject: [PATCH 01/23] Add a CI workflow for the toolchain and SDK

---
 .github/workflows/main.yml | 64 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 .github/workflows/main.yml

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
new file mode 100644
index 00000000..93e57372
--- /dev/null
+++ b/.github/workflows/main.yml
@@ -0,0 +1,64 @@
+# This is a basic workflow to help you get started with Actions
+
+name: CI
+
+# Controls when the action will run. Triggers the workflow on push or pull request
+# events but only for the master branch
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build-toolchain:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        # we don't need submodules for building the toolchain
+
+      # toolchain takes ~40min to build, so we want to avoid that whenever possible!
+      - uses: actions/cache@v2
+        id: toolchain-cache
+        with:
+          path: ndless-sdk/toolchain/install
+          # gcc/binutils/etc versions are in build_toolchain.sh, so that'll be part of our cache key
+          key: ${{ runner.os }}-${{ hashFiles('ndless-sdk/toolchain/build_toolchain.sh') }}
+      - name: Install dependencies
+        if: steps.toolchain-cache.outputs.cache-hit != 'true'
+        run: sudo apt install -y libmpfr-dev libmpc-dev
+      - name: Build
+        if: steps.toolchain-cache.outputs.cache-hit != 'true'
+        working-directory: ndless-sdk/toolchain
+        run: ./build_toolchain.sh
+      
+      - name: Upload built toolchain
+        uses: actions/upload-artifact@v2
+        with:
+          name: toolchain
+          path: ndless-sdk/toolchain/install
+  build-sdk:
+    needs: build-toolchain
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          submodules: 'recursive'
+          fetch-depth: 0 # submodule checkout does not work with depth=1 (the default)
+      
+      - name: Download built toolchain
+        uses: actions/download-artifact@v2
+        with:
+          name: toolchain
+          path: ndless-sdk/toolchain/install
+      - name: Set up PATH
+        run: |
+          echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/toolchain/install/bin"
+          echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/bin"
+      - name: Install dependencies
+        run: sudo apt install -y libboost-program-options-dev
+      - name: Build
+        run: make

From 81a887f6404c92e999e757cb7b8bec9ebb0b49a3 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 15:03:04 +0200
Subject: [PATCH 02/23] CI: fix toolchain permissions

---
 .github/workflows/main.yml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 93e57372..38a80119 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -54,6 +54,9 @@ jobs:
         with:
           name: toolchain
           path: ndless-sdk/toolchain/install
+      # necessary because +x isn't retained in the artifact
+      - name: Fix toolchain permissions
+        run: chmod +x ndless-sdk/toolchain/install/bin/*
       - name: Set up PATH
         run: |
           echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/toolchain/install/bin"

From 7b7541f366cf0fd32a14beef097497417703fe14 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 15:12:50 +0200
Subject: [PATCH 03/23] CI: use tar to accelerate artifacts

---
 .github/workflows/main.yml | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 38a80119..a39e04ee 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -33,12 +33,15 @@ jobs:
         if: steps.toolchain-cache.outputs.cache-hit != 'true'
         working-directory: ndless-sdk/toolchain
         run: ./build_toolchain.sh
+      - name: Package toolchain
+        if: steps.toolchain-cache.outputs.cache-hit != 'true'
+        run: tar -cvf toolchain.tar ndless-sdk/toolchain/install
       
       - name: Upload built toolchain
         uses: actions/upload-artifact@v2
         with:
           name: toolchain
-          path: ndless-sdk/toolchain/install
+          path: toolchain.tar
   build-sdk:
     needs: build-toolchain
     runs-on: ubuntu-latest
@@ -53,10 +56,9 @@ jobs:
         uses: actions/download-artifact@v2
         with:
           name: toolchain
-          path: ndless-sdk/toolchain/install
-      # necessary because +x isn't retained in the artifact
-      - name: Fix toolchain permissions
-        run: chmod +x ndless-sdk/toolchain/install/bin/*
+          path: toolchain.tar
+      - name: Extract toolchain
+        run: tar -xvf toolchain.tar ndless-sdk/toolchain/install
       - name: Set up PATH
         run: |
           echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/toolchain/install/bin"

From 6f268d549de7f3971f33de56e264cffae3db9ae9 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 15:14:55 +0200
Subject: [PATCH 04/23] CI: temporarily force packaging the toolchain, and gz
 it

---
 .github/workflows/main.yml | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index a39e04ee..4f18dc0b 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -23,7 +23,7 @@ jobs:
       - uses: actions/cache@v2
         id: toolchain-cache
         with:
-          path: ndless-sdk/toolchain/install
+          path: toolchain.tar.gz
           # gcc/binutils/etc versions are in build_toolchain.sh, so that'll be part of our cache key
           key: ${{ runner.os }}-${{ hashFiles('ndless-sdk/toolchain/build_toolchain.sh') }}
       - name: Install dependencies
@@ -34,8 +34,7 @@ jobs:
         working-directory: ndless-sdk/toolchain
         run: ./build_toolchain.sh
       - name: Package toolchain
-        if: steps.toolchain-cache.outputs.cache-hit != 'true'
-        run: tar -cvf toolchain.tar ndless-sdk/toolchain/install
+        run: tar -cvzf toolchain.tar.gz ndless-sdk/toolchain/install
       
       - name: Upload built toolchain
         uses: actions/upload-artifact@v2
@@ -58,7 +57,7 @@ jobs:
           name: toolchain
           path: toolchain.tar
       - name: Extract toolchain
-        run: tar -xvf toolchain.tar ndless-sdk/toolchain/install
+        run: tar -xvzf toolchain.tar.gz ndless-sdk/toolchain/install
       - name: Set up PATH
         run: |
           echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/toolchain/install/bin"

From bdbc74404aff3f805142481bb6c7c3c019549807 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 15:16:39 +0200
Subject: [PATCH 05/23] CI: skip packaging again if there's a cache

---
 .github/workflows/main.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 4f18dc0b..c4fe4dd5 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -34,6 +34,7 @@ jobs:
         working-directory: ndless-sdk/toolchain
         run: ./build_toolchain.sh
       - name: Package toolchain
+        if: steps.toolchain-cache.outputs.cache-hit != 'true'
         run: tar -cvzf toolchain.tar.gz ndless-sdk/toolchain/install
       
       - name: Upload built toolchain

From d9730bf1c125606289634ec2b332ebf641d59cab Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 15:59:54 +0200
Subject: [PATCH 06/23] CI: fix paths

---
 .github/workflows/main.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index c4fe4dd5..b160a966 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -41,7 +41,7 @@ jobs:
         uses: actions/upload-artifact@v2
         with:
           name: toolchain
-          path: toolchain.tar
+          path: toolchain.tar.gz
   build-sdk:
     needs: build-toolchain
     runs-on: ubuntu-latest
@@ -56,7 +56,7 @@ jobs:
         uses: actions/download-artifact@v2
         with:
           name: toolchain
-          path: toolchain.tar
+          path: toolchain.tar.gz
       - name: Extract toolchain
         run: tar -xvzf toolchain.tar.gz ndless-sdk/toolchain/install
       - name: Set up PATH

From 084d251c3f3e5ab51c7265461dba91275d1ef006 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 16:09:52 +0200
Subject: [PATCH 07/23] CI: fix artifact download path

---
 .github/workflows/main.yml | 1 -
 1 file changed, 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index b160a966..360e856d 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -56,7 +56,6 @@ jobs:
         uses: actions/download-artifact@v2
         with:
           name: toolchain
-          path: toolchain.tar.gz
       - name: Extract toolchain
         run: tar -xvzf toolchain.tar.gz ndless-sdk/toolchain/install
       - name: Set up PATH

From 3727203bfb421e2acd65603ba086242861fa118b Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 16:17:59 +0200
Subject: [PATCH 08/23] CI: minor formatting

---
 .github/workflows/main.yml | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 360e856d..4ecf2a0c 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -1,5 +1,3 @@
-# This is a basic workflow to help you get started with Actions
-
 name: CI
 
 # Controls when the action will run. Triggers the workflow on push or pull request
@@ -45,6 +43,7 @@ jobs:
   build-sdk:
     needs: build-toolchain
     runs-on: ubuntu-latest
+    
     steps:
       - name: Checkout
         uses: actions/checkout@v2

From ade4707fecba5546753ee7e57dcc83bba6265bae Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 16:29:30 +0200
Subject: [PATCH 09/23] CI: expand SDK build to more OSs

macOS failure is expected at this time, see https://github.com/ndless-nspire/Ndless/pull/200#issuecomment-649155030
---
 .github/workflows/main.yml | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 4ecf2a0c..dc63e04e 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -42,7 +42,11 @@ jobs:
           path: toolchain.tar.gz
   build-sdk:
     needs: build-toolchain
-    runs-on: ubuntu-latest
+    
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-16.04, ubuntu-18.04, macos-10.15]
     
     steps:
       - name: Checkout

From e223fba7e095f12a78a5d8cf9a3139f1bbc63a4e Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 16:35:55 +0200
Subject: [PATCH 10/23] CI: remove macOS for now

more steps (including a separate toolchain build for macOS) are needed for this
---
 .github/workflows/main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index dc63e04e..5c026bfe 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -46,7 +46,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-16.04, ubuntu-18.04, macos-10.15]
+        os: [ubuntu-16.04, ubuntu-18.04]
     
     steps:
       - name: Checkout

From 94594a4af037d070033e3a1176fbece2f0974b01 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 18:05:11 +0200
Subject: [PATCH 11/23] CI: install necessary dependencies

---
 .github/workflows/main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 5c026bfe..5556aa4c 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -66,6 +66,6 @@ jobs:
           echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/toolchain/install/bin"
           echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/bin"
       - name: Install dependencies
-        run: sudo apt install -y libboost-program-options-dev
+        run: sudo apt install -y libboost-program-options-dev libmpfr-dev libmpc-dev
       - name: Build
         run: make

From 201f0041b77be03e2b9f5ec7df548b710503dff6 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 18:25:59 +0200
Subject: [PATCH 12/23] CI: separate toolchain for each OS

---
 .github/workflows/main.yml | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 5556aa4c..7bcb401f 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -10,7 +10,10 @@ on:
 
 jobs:
   build-toolchain:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-16.04, ubuntu-18.04]
 
     steps:
       - name: Checkout
@@ -38,7 +41,7 @@ jobs:
       - name: Upload built toolchain
         uses: actions/upload-artifact@v2
         with:
-          name: toolchain
+          name: toolchain-${{ runner.os }}
           path: toolchain.tar.gz
   build-sdk:
     needs: build-toolchain
@@ -58,7 +61,7 @@ jobs:
       - name: Download built toolchain
         uses: actions/download-artifact@v2
         with:
-          name: toolchain
+          name: toolchain-${{ runner.os }}
       - name: Extract toolchain
         run: tar -xvzf toolchain.tar.gz ndless-sdk/toolchain/install
       - name: Set up PATH

From e050dd8a3c9efe13db5e59604655cea643230399 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 18:27:41 +0200
Subject: [PATCH 13/23] CI: add Ubuntu 20.04

---
 .github/workflows/main.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 7bcb401f..53e558a9 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-16.04, ubuntu-18.04]
+        os: [ubuntu-16.04, ubuntu-18.04, ubuntu-20.04]
 
     steps:
       - name: Checkout
@@ -49,7 +49,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-16.04, ubuntu-18.04]
+        os: [ubuntu-16.04, ubuntu-18.04, ubuntu-20.04]
     
     steps:
       - name: Checkout

From d2de45568396ced0d48ef3aba995895213522648 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 4 Aug 2020 18:30:48 +0200
Subject: [PATCH 14/23] CI: use matrix.os instead of runner.os

---
 .github/workflows/main.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 53e558a9..c5c7fe7b 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -26,7 +26,7 @@ jobs:
         with:
           path: toolchain.tar.gz
           # gcc/binutils/etc versions are in build_toolchain.sh, so that'll be part of our cache key
-          key: ${{ runner.os }}-${{ hashFiles('ndless-sdk/toolchain/build_toolchain.sh') }}
+          key: ${{ matrix.os }}-${{ hashFiles('ndless-sdk/toolchain/build_toolchain.sh') }}
       - name: Install dependencies
         if: steps.toolchain-cache.outputs.cache-hit != 'true'
         run: sudo apt install -y libmpfr-dev libmpc-dev
@@ -41,7 +41,7 @@ jobs:
       - name: Upload built toolchain
         uses: actions/upload-artifact@v2
         with:
-          name: toolchain-${{ runner.os }}
+          name: toolchain-${{ matrix.os }}
           path: toolchain.tar.gz
   build-sdk:
     needs: build-toolchain
@@ -61,7 +61,7 @@ jobs:
       - name: Download built toolchain
         uses: actions/download-artifact@v2
         with:
-          name: toolchain-${{ runner.os }}
+          name: toolchain-${{ matrix.os }}
       - name: Extract toolchain
         run: tar -xvzf toolchain.tar.gz ndless-sdk/toolchain/install
       - name: Set up PATH

From 96d7dde5ab680e97df0faf193a6ec327c3826b69 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Wed, 5 Aug 2020 14:19:04 +0200
Subject: [PATCH 15/23] Update .github/workflows/main.yml

use -j4 for make

Co-authored-by: Fabian Vogt <fabian@ritter-vogt.de>
---
 .github/workflows/main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index c5c7fe7b..d8f21fcf 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -71,4 +71,4 @@ jobs:
       - name: Install dependencies
         run: sudo apt install -y libboost-program-options-dev libmpfr-dev libmpc-dev
       - name: Build
-        run: make
+        run: make -j4

From 0658eff445bcd0a215c198b9960bdbe5aad3b189 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Wed, 5 Aug 2020 14:49:36 +0200
Subject: [PATCH 16/23] CI: merge jobs into one

---
 .github/workflows/main.yml | 39 +++++++++++++-------------------------
 1 file changed, 13 insertions(+), 26 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index d8f21fcf..35f002e8 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -9,7 +9,7 @@ on:
     branches: [ master ]
 
 jobs:
-  build-toolchain:
+  build:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -18,19 +18,25 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
-        # we don't need submodules for building the toolchain
+        # we don't need submodules for building the toolchain, but we do for everything else
+        with:
+          submodules: 'recursive'
+          fetch-depth: 0 # submodule checkout does not work with depth=1 (the default)
 
-      # toolchain takes ~40min to build, so we want to avoid that whenever possible!
+      # build the toolchain first
+      # it takes ~40min to build, so we want to avoid that whenever possible!
       - uses: actions/cache@v2
         id: toolchain-cache
         with:
-          path: toolchain.tar.gz
+          path: |
+            toolchain.tar.gz
+            ndless-sdk/toolchain/install
           # gcc/binutils/etc versions are in build_toolchain.sh, so that'll be part of our cache key
           key: ${{ matrix.os }}-${{ hashFiles('ndless-sdk/toolchain/build_toolchain.sh') }}
       - name: Install dependencies
         if: steps.toolchain-cache.outputs.cache-hit != 'true'
         run: sudo apt install -y libmpfr-dev libmpc-dev
-      - name: Build
+      - name: Build toolchain
         if: steps.toolchain-cache.outputs.cache-hit != 'true'
         working-directory: ndless-sdk/toolchain
         run: ./build_toolchain.sh
@@ -43,32 +49,13 @@ jobs:
         with:
           name: toolchain-${{ matrix.os }}
           path: toolchain.tar.gz
-  build-sdk:
-    needs: build-toolchain
-    
-    runs-on: ${{ matrix.os }}
-    strategy:
-      matrix:
-        os: [ubuntu-16.04, ubuntu-18.04, ubuntu-20.04]
-    
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-        with:
-          submodules: 'recursive'
-          fetch-depth: 0 # submodule checkout does not work with depth=1 (the default)
       
-      - name: Download built toolchain
-        uses: actions/download-artifact@v2
-        with:
-          name: toolchain-${{ matrix.os }}
-      - name: Extract toolchain
-        run: tar -xvzf toolchain.tar.gz ndless-sdk/toolchain/install
+      # actual build starts here
       - name: Set up PATH
         run: |
           echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/toolchain/install/bin"
           echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/bin"
       - name: Install dependencies
-        run: sudo apt install -y libboost-program-options-dev libmpfr-dev libmpc-dev
+        run: sudo apt install -y libboost-program-options-dev
       - name: Build
         run: make -j4

From a17785ea343db3a520da52015ad8a3dbb3d0b88f Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Wed, 5 Aug 2020 14:56:36 +0200
Subject: [PATCH 17/23] CI: always install toolchain dependencies

---
 .github/workflows/main.yml | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 35f002e8..ea88affb 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -23,6 +23,10 @@ jobs:
           submodules: 'recursive'
           fetch-depth: 0 # submodule checkout does not work with depth=1 (the default)
 
+      # needed both at compile- and runtime for the toolchain
+      - name: Install dependencies
+        run: sudo apt install -y libgmp-dev libmpfr-dev libmpc-dev
+
       # build the toolchain first
       # it takes ~40min to build, so we want to avoid that whenever possible!
       - uses: actions/cache@v2
@@ -33,9 +37,6 @@ jobs:
             ndless-sdk/toolchain/install
           # gcc/binutils/etc versions are in build_toolchain.sh, so that'll be part of our cache key
           key: ${{ matrix.os }}-${{ hashFiles('ndless-sdk/toolchain/build_toolchain.sh') }}
-      - name: Install dependencies
-        if: steps.toolchain-cache.outputs.cache-hit != 'true'
-        run: sudo apt install -y libmpfr-dev libmpc-dev
       - name: Build toolchain
         if: steps.toolchain-cache.outputs.cache-hit != 'true'
         working-directory: ndless-sdk/toolchain

From a14e1c5e2d2d531ce6a69b9f36cf15a930193d68 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Wed, 5 Aug 2020 15:03:51 +0200
Subject: [PATCH 18/23] CI: clarify a step

---
 .github/workflows/main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index ea88affb..dc8b509b 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -24,7 +24,7 @@ jobs:
           fetch-depth: 0 # submodule checkout does not work with depth=1 (the default)
 
       # needed both at compile- and runtime for the toolchain
-      - name: Install dependencies
+      - name: Install toolchain dependencies
         run: sudo apt install -y libgmp-dev libmpfr-dev libmpc-dev
 
       # build the toolchain first

From c5b01fdd9e0fa80065c0827af44847c2923e927b Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Thu, 6 Aug 2020 00:49:15 +0200
Subject: [PATCH 19/23] CI: remove ubuntu-16.04

---
 .github/workflows/main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index dc8b509b..f0ca9826 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-16.04, ubuntu-18.04, ubuntu-20.04]
+        os: [ubuntu-18.04, ubuntu-20.04]
 
     steps:
       - name: Checkout

From a12225c8eedae83800d668d14af4a05c237cfd2f Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Thu, 6 Aug 2020 00:50:10 +0200
Subject: [PATCH 20/23] CI: simplify artifact upload

---
 .github/workflows/main.yml | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index f0ca9826..5a8901b3 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -33,7 +33,6 @@ jobs:
         id: toolchain-cache
         with:
           path: |
-            toolchain.tar.gz
             ndless-sdk/toolchain/install
           # gcc/binutils/etc versions are in build_toolchain.sh, so that'll be part of our cache key
           key: ${{ matrix.os }}-${{ hashFiles('ndless-sdk/toolchain/build_toolchain.sh') }}
@@ -41,15 +40,12 @@ jobs:
         if: steps.toolchain-cache.outputs.cache-hit != 'true'
         working-directory: ndless-sdk/toolchain
         run: ./build_toolchain.sh
-      - name: Package toolchain
-        if: steps.toolchain-cache.outputs.cache-hit != 'true'
-        run: tar -cvzf toolchain.tar.gz ndless-sdk/toolchain/install
       
       - name: Upload built toolchain
         uses: actions/upload-artifact@v2
         with:
           name: toolchain-${{ matrix.os }}
-          path: toolchain.tar.gz
+          path: ndless-sdk/toolchain/install
       
       # actual build starts here
       - name: Set up PATH

From 50b761a91e8770e137b4a7c3f2fe441b6a29a6dc Mon Sep 17 00:00:00 2001
From: fridtjof <2780577+fridtjof@users.noreply.github.com>
Date: Mon, 10 Aug 2020 02:08:22 +0200
Subject: [PATCH 21/23] Revert "CI: simplify artifact upload"

This reverts commit 8c0111370ac399fac84cbb889d57249ce9cb1471.
---
 .github/workflows/main.yml | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 5a8901b3..f0ca9826 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -33,6 +33,7 @@ jobs:
         id: toolchain-cache
         with:
           path: |
+            toolchain.tar.gz
             ndless-sdk/toolchain/install
           # gcc/binutils/etc versions are in build_toolchain.sh, so that'll be part of our cache key
           key: ${{ matrix.os }}-${{ hashFiles('ndless-sdk/toolchain/build_toolchain.sh') }}
@@ -40,12 +41,15 @@ jobs:
         if: steps.toolchain-cache.outputs.cache-hit != 'true'
         working-directory: ndless-sdk/toolchain
         run: ./build_toolchain.sh
+      - name: Package toolchain
+        if: steps.toolchain-cache.outputs.cache-hit != 'true'
+        run: tar -cvzf toolchain.tar.gz ndless-sdk/toolchain/install
       
       - name: Upload built toolchain
         uses: actions/upload-artifact@v2
         with:
           name: toolchain-${{ matrix.os }}
-          path: ndless-sdk/toolchain/install
+          path: toolchain.tar.gz
       
       # actual build starts here
       - name: Set up PATH

From ececbcb974ec245442289cb64e7e8bcdbcc8da94 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 6 Oct 2020 01:17:40 +0200
Subject: [PATCH 22/23] ci: remove artifact uploads

---
 .github/workflows/main.yml | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index f0ca9826..0dab132e 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -32,24 +32,13 @@ jobs:
       - uses: actions/cache@v2
         id: toolchain-cache
         with:
-          path: |
-            toolchain.tar.gz
-            ndless-sdk/toolchain/install
+          path: ndless-sdk/toolchain/install
           # gcc/binutils/etc versions are in build_toolchain.sh, so that'll be part of our cache key
           key: ${{ matrix.os }}-${{ hashFiles('ndless-sdk/toolchain/build_toolchain.sh') }}
       - name: Build toolchain
         if: steps.toolchain-cache.outputs.cache-hit != 'true'
         working-directory: ndless-sdk/toolchain
         run: ./build_toolchain.sh
-      - name: Package toolchain
-        if: steps.toolchain-cache.outputs.cache-hit != 'true'
-        run: tar -cvzf toolchain.tar.gz ndless-sdk/toolchain/install
-      
-      - name: Upload built toolchain
-        uses: actions/upload-artifact@v2
-        with:
-          name: toolchain-${{ matrix.os }}
-          path: toolchain.tar.gz
       
       # actual build starts here
       - name: Set up PATH

From 9e1a5d049380cc41d6d6ffa4565d668651866e61 Mon Sep 17 00:00:00 2001
From: Fridtjof Mund <2780577+fridtjof@users.noreply.github.com>
Date: Tue, 6 Oct 2020 02:12:28 +0200
Subject: [PATCH 23/23] CI: update PATH setup to use environment files

see https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/
---
 .github/workflows/main.yml | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 0dab132e..d1e94c6f 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -27,6 +27,7 @@ jobs:
       - name: Install toolchain dependencies
         run: sudo apt install -y libgmp-dev libmpfr-dev libmpc-dev
 
+      # ndless-sdk
       # build the toolchain first
       # it takes ~40min to build, so we want to avoid that whenever possible!
       - uses: actions/cache@v2
@@ -40,11 +41,11 @@ jobs:
         working-directory: ndless-sdk/toolchain
         run: ./build_toolchain.sh
       
-      # actual build starts here
+      # ndless
       - name: Set up PATH
         run: |
-          echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/toolchain/install/bin"
-          echo "::add-path::$GITHUB_WORKSPACE/ndless-sdk/bin"
+          echo "$GITHUB_WORKSPACE/ndless-sdk/toolchain/install/bin" >> $GITHUB_PATH
+          echo "$GITHUB_WORKSPACE/ndless-sdk/bin" >> $GITHUB_PATH
       - name: Install dependencies
         run: sudo apt install -y libboost-program-options-dev
       - name: Build