don't need fake dts either now we've removed u-boot

THOUGHTS.txt

@@ -2436,3 +2436,17 @@ Sun Sep 17 16:44:31 BST 2023
 Can we figure out which bits of the old doc are missing from the new
 one and just transplant those? Then we can merge it sooner
 instead of blocking on writig all the new stuff
+
+We need to find a nice place for an introduction to choosing
+rootfsType
+
+Mon Sep 18 17:07:56 BST 2023
+
+Let's see if we can hack up an aarch64 qemu port
+
+From https://gist.github.com/oznu/ac9efae7c24fd1f37f1d933254587aa4 :
+
+curl -L https://releases.linaro.org/components/kernel/uefi-linaro/latest/release/qemu64/QEMU_EFI.fd -O
+dd if=/dev/zero of=flash1.img bs=1M count=64
+dd if=/dev/zero of=flash0.img bs=1M count=64
+dd if=QEMU_EFI.fd of=flash0.img conv=notrunc

devices/qemu-aarch64/default.nix

@@ -0,0 +1,75 @@
+# This "device" generates images that can be used with the QEMU
+# emulator. The default output is a directory containing separate
+# kernel ("Image" format) and root filesystem (squashfs or jffs2)
+# images
+{
+  system = {
+    crossSystem = {
+      config = "aarch64-unknown-linux-musl";
+    };
+  };
+
+  module = {pkgs, config, ... }: {
+    kernel = {
+      src = pkgs.pkgsBuildBuild.fetchurl {
+        name = "linux.tar.gz";
+        url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.71.tar.gz";
+        hash = "sha256-yhO2cXIeIgUxkSZf/4aAsF11uxyh+UUZu6D1h92vCD8=";
+      };
+      config = {
+        CPU_LITTLE_ENDIAN= "y";
+        CPU_BIG_ENDIAN= "n";
+
+        VIRTUALIZATION = "y";
+        PCI_HOST_GENERIC="y";
+
+        MTD = "y";
+        MTD_BLOCK2MTD = "y";
+        MTD_BLKDEVS = "y";
+        MTD_BLOCK = "y";
+
+        VIRTIO_MENU = "y";
+        PCI = "y";
+        VIRTIO_PCI = "y";
+        BLOCK = "y";
+        VIRTIO_BLK = "y";
+        NETDEVICES = "y";
+        VIRTIO_NET = "y";
+
+        # https://stackoverflow.com/a/68340492
+        CMDLINE="\"earlycon=smh console=ttyAMA0\"";
+        CMDLINE_FROM_BOOTLOADER = "y";
+
+        SERIAL_EARLYCON_ARM_SEMIHOST = "y"; # earlycon=smh
+        SERIAL_AMBA_PL011 = "y";
+        SERIAL_AMBA_PL011_CONSOLE = "y";
+      };
+    };
+    hardware =
+      let
+        mac80211 =  pkgs.mac80211.override {
+          drivers = ["mac80211_hwsim"];
+          klibBuild = config.system.outputs.kernel.modulesupport;
+        };
+      in {
+        defaultOutput = "vmroot";
+        loadAddress = "0x0";
+        entryPoint  = "0x0";
+        rootDevice = "/dev/mtd1";
+
+        flash.eraseBlockSize = "65536"; # c.f. pkgs/mips-vm/mips-vm.sh
+        networkInterfaces =
+          let inherit (config.system.service.network) link;
+          in {
+            wan = link.build { ifname = "eth0"; };
+            lan = link.build { ifname = "eth1"; };
+
+            wlan_24 = link.build {
+              ifname = "wlan0";
+              dependencies = [ mac80211 ];
+            };
+          };
+      };
+
+  };
+}

kernel/uimage.nix

@@ -6,6 +6,7 @@
 } :
 let
   objcopy = "${stdenv.cc.bintools.targetPrefix}objcopy";
+  arch = "arm64";
 in {
   kernel
 , commandLine
@@ -40,7 +41,7 @@ stdenv.mkDerivation {
   buildPhase = ''
     ${objcopy} -O binary -R .reginfo -R .notes -R .note -R .comment -R .mdebug -R .note.gnu.build-id -S vmlinux.elf vmlinux.bin
     rm -f vmlinux.bin.lzma ; lzma -k -z  vmlinux.bin
-    mkimage -A mips -O linux -T kernel -C lzma -a ${loadAddress} -e ${entryPoint} -n 'MIPS Liminix Linux ${extraName}' -d vmlinux.bin.lzma kernel.uimage
+    mkimage -A ${arch} -O linux -T kernel -C lzma -a ${loadAddress} -e ${entryPoint} -n '${arch} Liminix Linux ${extraName}' -d vmlinux.bin.lzma kernel.uimage
   '';
   installPhase = ''
     cp kernel.uimage $out

modules/kernel.nix

@@ -56,9 +56,9 @@ in {
         MODULE_SIG = if modular then "y" else "n";
         DEBUG_FS = "y";
 
-        MIPS_BOOTLOADER_CMDLINE_REQUIRE_COOKIE = "y";
+        # MIPS_BOOTLOADER_CMDLINE_REQUIRE_COOKIE = "y";
-        MIPS_BOOTLOADER_CMDLINE_COOKIE = "\"liminix\"";
+        # MIPS_BOOTLOADER_CMDLINE_COOKIE = "\"liminix\"";
-        MIPS_CMDLINE_DTB_EXTEND = "y";
+        # MIPS_CMDLINE_DTB_EXTEND = "y";
 
         # basic networking protocols
         NET = "y";

modules/outputs.nix

@@ -76,11 +76,12 @@ in
         inherit dtb;
       };
       # could use trivial-builders.linkFarmFromDrvs here?
-      vmroot = pkgs.runCommand "qemu" {} ''
+      vmroot = pkgs.runCommandCC "vmroot" {} ''
         mkdir $out
         cd $out
         ln -s ${config.system.outputs.rootfs} rootfs
         ln -s ${kernel} vmlinux
+        ${pkgs.stdenv.cc.targetPrefix}objcopy -O binary -S ${kernel} Image
         ln -s ${manifest} manifest
         ln -s ${kernel.headers} build
       '';

pkgs/kernel/default.nix

@@ -28,7 +28,7 @@ stdenv.mkDerivation rec {
     "-I${openssl.dev}/include -L${openssl.out}/lib -L${ncurses.out}/lib";
   PKG_CONFIG_PATH = "./pkgconfig";
   CROSS_COMPILE = stdenv.cc.bintools.targetPrefix;
-  ARCH = "mips";  # kernel uses "mips" here for both mips and mipsel
+  ARCH = "arm64";
   KBUILD_BUILD_HOST = "liminix.builder";
 
   dontStrip = true;
@@ -47,7 +47,7 @@ stdenv.mkDerivation rec {
   ];
 
   patches = [
-    ./cmdline-cookie.patch
+#    ./cmdline-cookie.patch
   ];
 
   # this is here to work around what I think is a bug in nixpkgs

pkgs/mips-vm/mips-vm.sh

@@ -42,10 +42,13 @@ fi
 
 INIT=${INIT-/bin/init}
 echo $QEMU_OPTIONS
-qemu-system-mips \
+
-    -M malta -m 256 \
+qemu-system-aarch64 \
+    -M virt  -m 512 \
     -echr 16 \
-    -append "liminix default console=ttyS0,38400n8 panic=10 oops=panic init=$INIT loglevel=8 root=/dev/mtdblock0 block2mtd.block2mtd=/dev/vda,65536" \
+    -append "liminix default earlycon=smh console=ttyAMA0,38400n8 panic=10 oops=panic init=$INIT loglevel=8 root=/dev/mtdblock0 block2mtd.block2mtd=/dev/vda,65536" \
+    -semihosting \
+    -cpu cortex-a72 \
     -drive file=$rootfs,format=raw,readonly=off,if=virtio,index=0 \
     ${initramfs} \
     -netdev socket,id=access,mcast=230.0.0.1:1234,localaddr=127.0.0.1 \

shell.nix

@@ -1,7 +1,7 @@
 let
   nixpkgs = <nixpkgs>;
   liminix = (import ./default.nix {
-    device = (import ./devices/qemu);
+    device = (import ./devices/qemu-aarch64);
     liminix-config = ./vanilla-configuration.nix;
     inherit nixpkgs;
   });