From 6489a394242a4daa0b44c1b778716b07eedf0e08 Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Sun, 5 Nov 2023 20:56:25 +0000
Subject: [PATCH] qemu armv7

---
 ci.nix                                |  2 +-
 devices/qemu-armv7l/default.nix       | 78 +++++++++++++++++++++++++++
 modules/arch/arm.nix                  |  9 ++++
 pkgs/run-liminix-vm/run-liminix-vm.sh |  8 +++
 4 files changed, 96 insertions(+), 1 deletion(-)
 create mode 100644 devices/qemu-armv7l/default.nix
 create mode 100644 modules/arch/arm.nix

diff --git a/ci.nix b/ci.nix
index 0f125df..085c7fe 100644
--- a/ci.nix
+++ b/ci.nix
@@ -9,7 +9,7 @@ let
   borderVmConf =  ./bordervm.conf-example.nix;
   inherit (pkgs.lib.attrsets) genAttrs;
   devices = {
-    virt = [ "qemu" "qemu-aarch64" ];
+    virt = [ "qemu" "qemu-aarch64" "qemu-armv7l" ];
     hw = [ "gl-ar750" "gl-mt300n-v2" "gl-mt300a"  ];
   };
   vanilla = ./vanilla-configuration.nix;
diff --git a/devices/qemu-armv7l/default.nix b/devices/qemu-armv7l/default.nix
new file mode 100644
index 0000000..149f793
--- /dev/null
+++ b/devices/qemu-armv7l/default.nix
@@ -0,0 +1,78 @@
+# 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 =  "armv7l-unknown-linux-musleabihf";
+    };
+  };
+
+  # this device is described by the "qemu" device
+  description = "";
+
+  module = {pkgs, config, ... }: {
+    imports = [ ../../modules/arch/arm.nix ];
+    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 = {
+        PCI_HOST_GENERIC = "y";
+        PCI = "y";
+        ARCH_VIRT = "y";
+
+        VFP = "y";
+        NEON = "y";
+        AEABI = "y";
+
+        MTD = "y";
+        MTD_BLOCK = "y";
+        MTD_CMDLINE_PARTS = "y";
+        MTD_PHRAM = "y";
+
+        VIRTIO_MENU = "y";
+        VIRTIO_PCI = "y";
+        BLOCK = "y";
+        VIRTIO_BLK = "y";
+        VIRTIO_NET = "y";
+
+        SERIAL_EARLYCON_ARM_SEMIHOST = "y"; # earlycon=smh
+        SERIAL_AMBA_PL011 = "y";
+        SERIAL_AMBA_PL011_CONSOLE = "y";
+      };
+    };
+    boot.commandLine = [
+      "console=ttyAMA0"
+    ];
+    hardware =
+      let
+        mac80211 =  pkgs.mac80211.override {
+          drivers = ["mac80211_hwsim"];
+          klibBuild = config.system.outputs.kernel.modulesupport;
+        };
+      in {
+        defaultOutput = "vmroot";
+        loadAddress = "0x00010000";
+        entryPoint  = "0x00010000";
+        rootDevice = "/dev/mtdblock0";
+
+        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 ];
+            };
+          };
+      };
+
+  };
+}
diff --git a/modules/arch/arm.nix b/modules/arch/arm.nix
new file mode 100644
index 0000000..474f780
--- /dev/null
+++ b/modules/arch/arm.nix
@@ -0,0 +1,9 @@
+{ lib, lim, pkgs, config, ...}:
+{
+  config = {
+    kernel.config = {
+      OF = "y";
+    };
+    hardware.ram.startAddress = lim.parseInt "0x40000000";
+  };
+}
diff --git a/pkgs/run-liminix-vm/run-liminix-vm.sh b/pkgs/run-liminix-vm/run-liminix-vm.sh
index 637977a..b7afeef 100755
--- a/pkgs/run-liminix-vm/run-liminix-vm.sh
+++ b/pkgs/run-liminix-vm/run-liminix-vm.sh
@@ -52,6 +52,14 @@ case "$arch" in
     aarch64)
 	QEMU="qemu-system-aarch64 -M virt -semihosting -cpu cortex-a72"
 	;;
+    arm)
+	# https://bugs.launchpad.net/qemu/+bug/1790975
+	QEMU="qemu-system-arm -M virt,highmem=off -cpu cortex-a15"
+	;;
+    *)
+	echo "unrecognised arch $arch"
+	exit 1;
+	;;
 esac
 
 phram="mtdparts=phram0:16M(rootfs) phram.phram=phram0,${PHRAM_ADDRESS},16Mi,65536 root=/dev/mtdblock0";