use openwrt kernel for gl-ar750

presently this is used to reference the appropriate kernel and (if
needed) openwrt source trees, but I would not be surprised if we find
other uses

THOUGHTS.txt

@@ -341,3 +341,63 @@ For Liminix we're not going to do that.
    PHRAM support)
 * it means we need to memmap out enough ram for the whole image inc kernel when really
   all we need to reserve is the rootfs bit
+
+
+Sat Oct  8 11:23:08 BST 2022
+
+"halt" and "reboot" don't work on gl-ar750
+
+Sat Oct  8 13:10:00 BST 2022
+
+Where do we go with this ar750?
+
+- wired networking
+- wifi
+
+
+Sun Oct  9 09:57:35 BST 2022
+
+We want to be able to package kernel modules as regular derivations, so that
+they get added to the filesystem
+
+This means they need access to kernel.modulesupport
+
+This means  kernel.modulesupport needs to be in pkgs too?
+
+This is fine, probably, but we'd like to avoid closing over vmlinux because
+there's no need for it to be in the filesystem
+
+Mon Oct 10 22:57:23 BST 2022
+
+The problem is that kernel kconfig options are manipulated in the
+liminix modules, which means that data must be (transitively) available
+to modules, so they can't be regular packages as they're tied so tightly
+to the exact config. Unless we define a second overlay that references
+the configuration object, but my head hurts when I start to think about that
+so maybe not.
+
+Tue Oct 11 00:00:13 BST 2022
+
+Building ag71xx (ethernet driver) as a module doesn't work because
+it references a symbol ath79_pll_base in the kernel that hasn't been
+marked with EXPORT_SYMBOL.
+
+We could forge an object file that "declares" it with a gross and disgusting hack like this
+
+$ echo > empty # not actually "empty", objcopy complains about that
+$ grep ath79_pll_base /nix/store/jcc114cd13xa8aa4mil35rlnmxnlmv09-vmlinux-mips-unknown-linux-musl-modulesupport/System.map
+ffffffff807b2094 B ath79_pll_base
+$ mips-unknown-linux-musl-objcopy   -I binary -O elf32-big --add-section .bss=empty  --add-symbol ath79_pll_base=.bss:0x807b2094  empty f.o
+
+I don't claim this is a good idea, just an idea. Thought was that we would not
+have to declare its type this way. Also it might not work with kaslr
+https://stackoverflow.com/a/68903503
+
+
+Backstory: why are we trying to build this as a module? because the
+openwrt fork of it seems to be a bit more advanced than the mainline,
+and I *suspect* that the mainline version doesn't work with our
+openwrt-based device tree which ahs the mdio as a nested node inside
+the ag71xx node - in mainline the driver seems to have all the mdio
+stuff inline. So, could we build the openwrt driver without patching
+the crap out of our kernel

default.nix

@@ -5,7 +5,7 @@
 
 let
   overlay = import ./overlay.nix;
-  nixpkgs = import <nixpkgs> ( device.system // {overlays = [overlay]; });
+  nixpkgs = import <nixpkgs> (device.system // {overlays = [overlay device.overlay]; });
   inherit (nixpkgs.pkgs) callPackage writeText liminix;
   inherit (nixpkgs.lib) concatStringsSep;
   config = (import ./merge-modules.nix) [
@@ -44,7 +44,7 @@ let
       let
         inherit (nixpkgs.lib.trivial) toHexString;
         uimageStart = 10485760; # 0xa00000
-        squashfsStart = uimageStart + 2 * 1024 * 1024;
+        squashfsStart = uimageStart + 4 * 1024 * 1024;
         squashfsSize = 8;
         cmd = "mtdparts=phram0:${toString squashfsSize}M(nix) phram.phram=phram0,0x${toHexString squashfsStart},${toString squashfsSize}Mi memmap=${toString squashfsSize}M\$0x${toHexString squashfsStart} root=1f00";
       in
@@ -56,16 +56,19 @@ let
           bootm 0x${toHexString uimageStart}
         '';
 
-    directory = nixpkgs.pkgs.runCommand "liminix" {} ''
+    directory = nixpkgs.pkgs.runCommand "liminix" {} (''
       mkdir $out
       cd $out
       ln -s ${squashfs} squashfs
       ln -s ${kernel.vmlinux} vmlinux
       ln -s ${manifest} manifest
+      ln -s ${kernel.vmlinux.modulesupport} build
+    '' +
+    (if device ? boot then ''
       ln -s ${uimage} uimage
       ${if phram then "ln -s ${boot-scr} boot.scr" else ""}
       ln -s ${boot-scr} flash.scr
-    '';
+    '' else ""));
     # this exists so that you can run "nix-store -q --tree" on it and find
     # out what's in the image, which is nice if it's unexpectedly huge
     manifest = writeText "manifest.json" (builtins.toJSON config.filesystem.contents);

devices/gl-ar750/default.nix

@@ -10,6 +10,9 @@
 # DIY users: the serial port connections have headers preinstalled
 # and don't need soldering
 
+# Mainline linux 5.19 doesn't have device-tree support for this device
+# or even for the SoC, so we use the extensive OpenWrt kernel patches
+
 {
   system = {
     crossSystem = {
@@ -20,11 +23,66 @@
       };
     };
   };
+
+  # We need to be able to import default.nix before we import nixpkgs
+  # because it has the system config to tell nixpkgs what arch to build for.
+  # But we also need some way to do things like fetchFromGitHub in the
+  # per-device config and we can only do that once we have a reference to
+  # pkgs
+
+  overlay = final: prev:
+    let
+      inherit (final) fetchFromGitHub fetchgit stdenvNoCC;
+      openwrt = fetchFromGitHub {
+        name = "openwrt-source";
+        repo = "openwrt";
+        owner = "openwrt";
+        rev = "a5265497a4f6da158e95d6a450cb2cb6dc085cab";
+        hash = "sha256-YYi4gkpLjbOK7bM2MGQjAyEBuXJ9JNXoz/JEmYf8xE8=";
+      };
+      mainline = fetchFromGitHub {
+        name = "kernel-source";
+        owner = "torvalds";
+        repo = "linux";
+        rev = "90c7e9b400c751dbd73885f494f421f90ca69721";
+        hash = "sha256-pq6QNa0PJVeheaZkuvAPD0rLuEeKrViKk65dz+y4kqo=";
+      };
+    in {
+      sources = {
+        inherit openwrt;
+        kernel = stdenvNoCC.mkDerivation {
+          name = "spindled-kernel-tree";
+          src = mainline;
+          phases = [
+            "unpackPhase" "patchPhase" "openWrtPatchPhase"
+            "patchScripts" "installPhase"
+          ];
+          patches = [ ../../kernel/random.patch ];
+          patchScripts = ''
+            patchShebangs scripts/
+          '';
+          openWrtPatchPhase = ''
+            cp -av ${openwrt}/target/linux/generic/files/* .
+            chmod -R u+w .
+            cp -av ${openwrt}/target/linux/ath79/files/* .
+            chmod -R u+w .
+            for i in ${openwrt}/target/linux/ath79/patches-5.15/* ; do patch --batch --forward -p1 < $i ;done
+          '';
+          installPhase = ''
+            mkdir -p $out
+            cp -a . $out
+          '';
+        };
+      };
+    };
   kernel = rec {
     checkedConfig = {
       "MIPS_ELF_APPENDED_DTB" = "y";
       OF = "y";
       USE_OF = "y";
+      ATH79 = "y";
+#      SOC_QCA955X = "y";        #  actually QCA9531, is this even right?
+      LIMINIX = "y";
       SERIAL_8250_CONSOLE = "y";
       SERIAL_8250 = "y";
       SERIAL_CORE_CONSOLE = "y";
@@ -39,13 +97,21 @@
       CONSOLE_LOGLEVEL_DEFAULT = "8";
       CONSOLE_LOGLEVEL_QUIET = "4";
 
-
       # "empty" initramfs source should create an initial
       # filesystem that has a /dev/console node and not much
       # else.  Note that pid 1 is started *before* the root
       # filesystem is mounted and it expects /dev/console to
       # be present already
       BLK_DEV_INITRD = "n";
+
+      NET = "y";
+      NETDEVICES = "y";
+      ETHERNET = "y";
+      NET_VENDOR_ATHEROS = "y";
+      AG71XX = "y";             # ethernet (qca,qca9530-eth)
+
+      MFD_SYSCON = "y";         # ethernet (compatible "syscon")
+
     };
     config = {
       CPU_LITTLE_ENDIAN= "n";

devices/qemu/default.nix

@@ -12,6 +12,21 @@
       };
     };
   };
+
+  overlay = final: prev:
+    let inherit (final) fetchFromGitHub;
+    in {
+      sources = {
+        kernel =  fetchFromGitHub {
+          name = "kernel-source";
+          owner = "torvalds";
+          repo = "linux";
+          rev = "3d7cb6b04c3f3115719235cc6866b10326de34cd";  # v5.19
+          hash = "sha256-OVsIRScAnrPleW1vbczRAj5L/SGGht2+GnvZJClMUu4=";
+        };
+      };
+    };
+
   kernel = {
     config = {
       SYSVIPC= "y";

kernel/default.nix

@@ -1,57 +1,19 @@
 {
   callPackage
-, buildPackages
-, stdenvNoCC
-, fetchFromGitHub
 
 , config
 , checkedConfig
+, sources
 }:
-let
+{
-  source = fetchFromGitHub {
-    owner = "torvalds";
-    repo = "linux";
-    rev = "3d7cb6b04c3f3115719235cc6866b10326de34cd";  # v5.19
-    hash = "sha256-OVsIRScAnrPleW1vbczRAj5L/SGGht2+GnvZJClMUu4=";
-  };
-
-  # The kernel is huge and takes a long time just to
-  # download and unpack. This derivation creates
-  # a source tree in a suitable shape to build from -
-  # today it just patches some scripts but as we add
-  # support for boards/SoCs we expect the scope of
-  # "pre-treatment" to grow
-
-  tree = stdenvNoCC.mkDerivation {
-    name = "spindled-kernel-tree";
-    src = source;
-    phases = [ "unpackPhase" "patchScripts" "installPhase" ];
-    patchScripts = ''
-      patchShebangs scripts/
-    '';
-    installPhase = ''
-      mkdir -p $out
-      cp -a . $out
-    '';
-  };
-
-  openwrtSource = fetchFromGitHub {
-    repo = "openwrt";
-    owner = "openwrt";
-    rev = "a5265497a4f6da158e95d6a450cb2cb6dc085cab";
-    hash = "sha256-YYi4gkpLjbOK7bM2MGQjAyEBuXJ9JNXoz/JEmYf8xE8=";
-  };
-
-
-in rec {
   vmlinux = callPackage ./vmlinux.nix {
-    inherit tree config checkedConfig;
+    tree = sources.kernel;
+    inherit config checkedConfig;
   };
 
   uimage = callPackage ./uimage.nix { };
 
   dtb = callPackage ./dtb.nix {
-    openwrt = openwrtSource;
+    inherit (sources) openwrt kernel;
-    kernel = tree;
   };
 }

kernel/random.patch

@@ -0,0 +1,9 @@
+diff --git a/Kconfig b/Kconfig
+index 745bc773f567..24a6ea92ee19 100644
+--- a/Kconfig
++++ b/Kconfig
+@@ -30,3 +30,4 @@ source "lib/Kconfig"
+ source "lib/Kconfig.debug"
+ 
+ source "Documentation/Kconfig"
++source "Kconfig.local"

kernel/vmlinux.nix

@@ -16,6 +16,17 @@ let writeConfig = name : config: writeText name
             config
           ));
     kconfigFile = writeConfig "kconfig" (config // checkedConfig);
+    # KLUDGE FIXME. some symbols we need to enable in some configurations don't
+    # have a prompt (!), so we can't turn them on just by adding FOO=y  and make oldconfig
+    #
+    # (!) yes, that was my reaction too
+    kconfigLocal = writeText "Kconfig.local" ''
+      config LIMINIX
+             prompt "Local symbols"
+             bool
+             default y
+             select SOC_QCA955X
+    '';
     checkedConfigFile = writeConfig "checked_kconfig" checkedConfig ;
     inherit lib; in
 stdenv.mkDerivation rec {
@@ -60,6 +71,7 @@ stdenv.mkDerivation rec {
     export KBUILD_OUTPUT=`pwd`
     cp ${kconfigFile} .config
     cp ${kconfigFile} .config.orig
+    cp ${kconfigLocal} Kconfig.local
     ( cd ${tree} && make V=1 olddefconfig )
   '';
 
@@ -74,14 +86,15 @@ stdenv.mkDerivation rec {
 
   KBUILD_BUILD_HOST = "liminix.builder";
   buildPhase = ''
-    make -C ${tree} vmlinux
+    make -C ${tree} vmlinux modules_prepare
   '';
 
   installPhase = ''
     ${CROSS_COMPILE}strip -d vmlinux
     cp vmlinux $out
-    make clean
     mkdir -p $modulesupport
+    cp .config $modulesupport/config
+    make clean
     cp -a . $modulesupport
   '';
 

modules/base.nix

@@ -53,6 +53,9 @@ in {
         IKCONFIG = "y";
         IKCONFIG_PROC = "y";
         PROC_FS = "y";
+
+        MODULES = "y";
+
         # s6-linux-init mounts this on /dev
         DEVTMPFS = "y";
         # some or all of these may be fix for "tmpfs: Unknown parameter 'mode'" error
@@ -64,6 +67,7 @@ in {
     };
     boot.commandLine = [
       "earlyprintk=serial,ttyS0 console=ttyS0,115200 panic=10 oops=panic init=/bin/init loglevel=8 rootfstype=squashfs"
+      "fw_devlink=off"
     ];
     users.root = {
       uid = 0; gid= 0; gecos = "Root of all evaluation";

overlay.nix

@@ -12,10 +12,19 @@ final: prev: {
   s6-init-bin =  final.callPackage ./pkgs/s6-init-bin {};
   s6-rc-database = final.callPackage ./pkgs/s6-rc-database {};
 
-  dnsmasq = prev.dnsmasq.override {
+
+  dnsmasq =
+    let d =  prev.dnsmasq.overrideAttrs(o: {
+          preBuild =  ''
+              makeFlagsArray=("COPTS=")
+          '';
+        });
+    in d.override {
     dbusSupport = false;
+    nettle = null;
   };
 
+
   tufted = final.callPackage ./pkgs/tufted {};
 
   pppoe = final.callPackage ./pkgs/pppoe {};

tests/kernel/run.sh

@@ -1,5 +1,5 @@
 set -e
-NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build '<liminix>' -I liminix-config=../smoke/configuration.nix --arg device "import <liminix/devices/$DEVICE.nix>" -A outputs.kernel.vmlinux -o vmlinux $*
+NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build '<liminix>' -I liminix-config=../smoke/configuration.nix --arg device "import <liminix/devices/$DEVICE>" -A outputs.kernel.vmlinux -o vmlinux $*
 
 TESTS=$(cat <<"EOF"
 

tests/module/run.sh

@@ -1,2 +1,2 @@
 set -e
-NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build --arg device "import <liminix/devices/qemu.nix>" test.nix
+NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build --arg device "import <liminix/devices/qemu>" test.nix

tests/pppoe/run.sh

@@ -14,7 +14,7 @@ fatal(){
 }
 trap fatal ERR
 
-NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build '<liminix>' -I liminix-config=./configuration.nix --arg device "import <liminix/devices/qemu.nix>" -A outputs.default $*
+NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build '<liminix>' -I liminix-config=./configuration.nix --arg device "import <liminix/devices/qemu>" -A outputs.default $*
 
 if ! ( echo "cont" | socat - unix-connect:../support/ppp-server/qemu-monitor); then
     echo "need pppoe server running"

tests/smoke/run.sh

@@ -1,5 +1,5 @@
 set -e
-NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build '<liminix>' -I liminix-config=./configuration.nix --arg device "import <liminix/devices/$DEVICE.nix>" -A outputs.squashfs -o smoke.img $*
+NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build '<liminix>' -I liminix-config=./configuration.nix --arg device "import <liminix/devices/$DEVICE>" -A outputs.squashfs -o smoke.img $*
 
 TESTS=$(cat <<"EOF"
 test -n "${TMPDIR}"

tests/wlan/run.sh

@@ -14,7 +14,7 @@ fatal(){
 }
 trap fatal ERR
 
-NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build '<liminix>' -I liminix-config=./configuration.nix --arg device "import <liminix/devices/qemu.nix>" -A outputs.default $*
+NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build '<liminix>' -I liminix-config=./configuration.nix --arg device "import <liminix/devices/qemu>" -A outputs.default $*