use "tftpboot" instead of "tftp" in u-boot commands

openwrt's u-boot installation doesn't accept the short form

devices/belkin-rt3200/default.nix

@@ -0,0 +1,181 @@
+# 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, lib, ... }:
+    let firmware = pkgs.stdenv.mkDerivation {
+          name = "wlan-firmware";
+          phases = ["installPhase"];
+          installPhase = ''
+            mkdir $out
+            cp ${pkgs.linux-firmware}/lib/firmware/mediatek/{mt7915,mt7615,mt7622}* $out
+          '';
+        };
+    in {
+    imports = [ ../../modules/arch/aarch64.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=";
+      };
+      extraPatchPhase = ''
+          ${pkgs.openwrt.applyPatches.mediatek}
+      '';
+      config = {
+        PCI = "y";
+        ARCH_MEDIATEK = "y";
+        # ARM_MEDIATEK_CPUFREQ = "y";
+
+        # needed for "Cannot find regmap for /infracfg@10000000"
+        MFD_SYSCON = "y";
+        MTK_INFRACFG = "y";
+
+        MTK_PMIC_WRAP = "y";
+        MTK_EFUSE="y";
+        # MTK_HSDMA="y";
+        MTK_SCPSYS="y";
+        MTK_SCPSYS_PM_DOMAINS="y";
+        # MTK_THERMAL="y";
+        MTK_TIMER="y";
+
+        COMMON_CLK_MT7622 = "y";
+        COMMON_CLK_MT7622_ETHSYS = "y";
+        COMMON_CLK_MT7622_HIFSYS = "y";
+        COMMON_CLK_MT7622_AUDSYS = "y";
+        PM_CLK="y";
+
+        REGMAP_MMIO = "y";
+        CLKSRC_MMIO = "y";
+        REGMAP = "y";
+
+        MEDIATEK_GE_PHY = "y";
+        # MEDIATEK_MT6577_AUXADC = "y";
+        # MEDIATEK_WATCHDOG = "y";
+        NET_MEDIATEK_SOC = "y";
+        NET_MEDIATEK_SOC_WED = "y";
+        NET_MEDIATEK_STAR_EMAC = "y"; # this enables REGMAP_MMIO
+        NET_VENDOR_MEDIATEK = "y";
+        PCIE_MEDIATEK = "y";
+
+        BLOCK = "y"; # move this to base option
+        NETDEVICES = "y";  # and this probably also
+
+        SPI_MASTER = "y";
+        SPI = "y";
+        SPI_MEM="y";
+        SPI_MTK_NOR="y";
+        SPI_MTK_SNFI = "y";
+
+        MTD = "y";
+        MTD_BLOCK = "y";
+        MTD_RAW_NAND = "y";
+        MTD_NAND_MTK = "y";
+        MTD_NAND_MTK_BMT = "y";      # Bad-block Management Table
+        MTD_NAND_ECC_MEDIATEK= "y";
+        MTD_NAND_ECC_SW_HAMMING= "y";
+        MTD_SPI_NAND= "y";
+        MTD_OF_PARTS = "y";
+        MTD_NAND_CORE= "y";
+        MTD_SPI_NOR= "y";
+        MTD_SPLIT_FIRMWARE= "y";
+        MTD_SPLIT_FIT_FW= "y";
+        MTD_UBI="y";
+        MTD_UBI_BEB_LIMIT="20";
+        MTD_UBI_BLOCK="y";
+        MTD_UBI_WL_THRESHOLD="4096";
+
+        MMC = "y";
+        MMC_BLOCK = "y";
+        MMC_CQHCI = "y";
+        MMC_MTK = "y";
+
+        # Distributed Switch Architecture is needed
+        # to make the ethernet ports visible
+        NET_DSA="y";
+        NET_DSA_MT7530="y";
+        NET_DSA_TAG_MTK="y";
+
+        PSTORE = "y";
+        PSTORE_RAM = "y";
+        PSTORE_CONSOLE = "y";
+        PSTORE_DEFLATE_COMPRESS = "n";
+
+        SERIAL_8250 = "y";
+        SERIAL_8250_CONSOLE = "y";
+        SERIAL_8250_MT6577="y";
+        # SERIAL_8250_NR_UARTS="3";
+        # SERIAL_8250_RUNTIME_UARTS="3";
+        SERIAL_OF_PLATFORM="y";
+      };
+    };
+    boot.commandLine = [
+      "console=ttyS0,115200"
+    ];
+    filesystem =
+      let inherit (pkgs.pseudofile) dir symlink;
+           in
+             dir {
+               lib = dir {
+                 firmware = dir {
+                   mediatek = symlink firmware;
+                 };
+               };
+             };
+
+    hardware =
+      let
+        openwrt = pkgs.openwrt;
+        mac80211 =  pkgs.mac80211.override {
+          drivers = [
+            "mt7615e"
+            "mt7915e"
+          ];
+          klibBuild = config.system.outputs.kernel.modulesupport;
+        };
+      in {
+        defaultOutput = "flashimage";
+        loadAddress = "0x41080000";
+        entryPoint  = "0x41080000";
+        rootDevice = "/dev/mtdblock0";
+        dts = {
+          src = "${openwrt.src}/target/linux/mediatek/dts/mt7622-linksys-e8450.dts";
+          includes =  [
+            "${openwrt.src}/target/linux/mediatek/dts"
+            "${config.system.outputs.kernel.modulesupport}/arch/arm64/boot/dts/mediatek/"
+          ];
+        };
+
+        flash.eraseBlockSize = "65536"; # c.f. pkgs/mips-vm/mips-vm.sh
+        networkInterfaces =
+          let
+            inherit (config.system.service.network) link;
+            inherit (config.system.service) bridge;
+          in rec {
+            wan = link.build { ifname = "wan"; };
+            lan1 = link.build { ifname = "lan1"; };
+            lan2 = link.build { ifname = "lan2"; };
+            lan3 = link.build { ifname = "lan3"; };
+            lan4 = link.build { ifname = "lan4"; };
+            lan = lan3;
+
+            wlan = link.build {
+              ifname = "wlan0";
+              dependencies = [ mac80211 ];
+            };
+            wlan5 = link.build {
+              ifname = "wlan1";
+              dependencies = [ mac80211 ];
+            };
+          };
+      };
+
+  };
+}

devices/qemu-aarch64/default.nix

@@ -42,6 +42,9 @@
         SERIAL_AMBA_PL011_CONSOLE = "y";
       };
     };
+    boot.commandLine = [
+      "console=ttyAMA0,38400"
+    ];
     hardware =
       let
         mac80211 =  pkgs.mac80211.override {

modules/arch/aarch64.nix

@@ -6,14 +6,11 @@
       CPU_BIG_ENDIAN= "n";
       # CMDLINE_FROM_BOOTLOADER availability is conditional
       # on CMDLINE being set to something non-empty
-      CMDLINE="\"console=ttyAMA0\"";
+      CMDLINE="\"empty=false\"";
       CMDLINE_FROM_BOOTLOADER = "y";
 
       OF = "y";
       # USE_OF = "y";
     };
-    boot.commandLine = [
-      "console=ttyAMA0,38400"
-    ];
   };
 }

modules/tftpboot.nix

@@ -42,27 +42,41 @@ in {
           ln -s ${o.manifest} manifest
           ln -s ${o.kernel.headers} build
           ln -s ${o.uimage} uimage
-          ln -s ${o.boot-scr} boot.scr
+          ln -s ${o.boot-scr}/dtb dtb
+          ln -s ${o.boot-scr}/script boot.scr
        '';
 
       boot-scr =
         let
           inherit (pkgs.lib.trivial) toHexString;
           o = config.system.outputs;
+          cmdline = concatStringsSep " " config.boot.commandLine;
         in
-          pkgs.buildPackages.runCommand "boot-scr" {} ''
+          pkgs.buildPackages.runCommand "boot-scr" { nativeBuildInputs = [ pkgs.pkgsBuildBuild.dtc ];  } ''
             uimageSize=$(($(stat -L -c %s ${o.uimage}) + 0x1000 &(~0xfff)))
-            rootfsStart=0x$(printf %x $((${cfg.loadAddress} + 0x100000 + $uimageSize)))
+            rootfsStart=0x$(printf %x $((${cfg.loadAddress} + 0x100000 + $uimageSize   &(~0xfffff) )))
             rootfsBytes=$(($(stat -L -c %s ${o.rootfs}) + 0x100000 &(~0xfffff)))
+            rootfsMb=$(($rootfsBytes >> 20))
             rootfsBytes=$(($rootfsBytes + ${toString cfg.freeSpaceBytes} ))
-            cmd="mtdparts=phram0:''${rootfsMb}M(rootfs) phram.phram=phram0,''${rootfsStart},''${rootfsBytes},${config.hardware.flash.eraseBlockSize} memmap=''${rootfsBytes}\$''${rootfsStart} root=/dev/mtdblock0";
+            cmd="mtdparts=phram0:''${rootfsMb}M(rootfs) phram.phram=phram0,''${rootfsStart},''${rootfsBytes},${config.hardware.flash.eraseBlockSize} root=/dev/mtdblock0";
 
-            cat > $out << EOF
+            dtbStart=$(printf %x $((${cfg.loadAddress} + $rootfsBytes + 0x100000 + $uimageSize )))
+
+            mkdir $out
+            dtc -I dtb -O dts -o tmp.dts ${o.dtb}
+            echo "/ { reserved-memory { phram: phram@$rootfsStart {compatible = \"phram\"; reg = <0x0 $rootfsStart 0x0 $(printf "0x%x" $rootfsBytes )>; }; }; } ;" >> tmp.dts
+            cat tmp.dts
+
+            dtc -I dts -O dtb -o $out/dtb tmp.dts
+            dtbBytes=$(($(stat -L -c %s $out/dtb) + 0x1000 &(~0xfff)))
+
+            cat > $out/script << EOF
             setenv serverip ${cfg.serverip}
             setenv ipaddr ${cfg.ipaddr}
-            setenv bootargs 'liminix $cmd'
-            tftp 0x$(printf %x ${cfg.loadAddress}) result/uimage ; tftp 0x$(printf %x $rootfsStart) result/rootfs
-            bootm 0x$(printf %x ${cfg.loadAddress})
+            setenv bootargs 'liminix ${cmdline} $cmd'
+            tftpboot 0x$(printf %x ${cfg.loadAddress}) result/uimage ; tftpboot 0x$(printf %x $rootfsStart) result/rootfs ; tftpboot 0x$dtbStart result/dtb
+            bootm 0x$(printf %x ${cfg.loadAddress}) - 0x$dtbStart
+            #
             EOF
           '';
     };

pkgs/kernel/default.nix

@@ -54,6 +54,7 @@ stdenv.mkDerivation rec {
 
   patches = [
     ./cmdline-cookie.patch
+    ./phram-allow-cached-mappings.patch
   ];
 
   # this is here to work around what I think is a bug in nixpkgs

pkgs/kernel/phram-allow-cached-mappings.patch

@@ -0,0 +1,47 @@
+From bb7e7aeb3d832059e33b1e76eb85d4680f77abf2 Mon Sep 17 00:00:00 2001
+From: Ben Hutchings <ben@decadent.org.uk>
+Date: Fri, 3 Jun 2016 01:08:36 +0100
+Subject: [PATCH] phram: Use memremap() to allow mapping of system RAM
+
+Using memremap() instead of ioremap() allows mapping a disk image in
+system RAM that has somehow been reserved.  It should fall back
+to ioremap() where necessary.
+
+Entirely untested, and I'm not convinced this is a good idea at all.
+---
+ drivers/mtd/devices/phram.c | 7 ++++---
+ 1 file changed, 4 insertions(+), 3 deletions(-)
+
+diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
+index 8b66e52ca3cc..0ea254e2ba51 100644
+--- a/drivers/mtd/devices/phram.c
++++ b/drivers/mtd/devices/phram.c
+@@ -88,7 +88,7 @@ static void unregister_devices(void)
+ 
+ 	list_for_each_entry_safe(this, safe, &phram_list, list) {
+ 		mtd_device_unregister(&this->mtd);
+-		iounmap(this->mtd.priv);
++		memunmap(this->mtd.priv);
+ 		kfree(this->mtd.name);
+ 		kfree(this);
+ 	}
+@@ -104,7 +104,8 @@ static int register_device(char *name, phys_addr_t start, size_t len)
+ 		goto out0;
+ 
+ 	ret = -EIO;
+-	new->mtd.priv = ioremap(start, len);
++	new->mtd.priv = memremap(start, len,
++				 MEMREMAP_WB | MEMREMAP_WT | MEMREMAP_WC);
+ 	if (!new->mtd.priv) {
+ 		pr_err("ioremap failed\n");
+ 		goto out1;
+@@ -134,7 +135,7 @@ static int register_device(char *name, phys_addr_t start, size_t len)
+ 	return 0;
+ 
+ out2:
+-	iounmap(new->mtd.priv);
++	memunmap(new->mtd.priv);
+ out1:
+ 	kfree(new);
+ out0:
+