Move qemu specific config to vm.nix

vm.nix

@@ -8,8 +8,11 @@
   ];
 
   boot = {
-    kernelParams = [ "boot.shell_on_fail" ];
-    #kernelPackages = lib.mkForce pkgs.linuxPackagesCustom;
+    kernelParams = [
+      "console=tty1"
+      "console=ttyS0,115200"
+      "boot.shell_on_fail"
+    ];
     consoleLogLevel = lib.mkDefault 7;
     initrd.kernelModules = [
       "virtio_pci"
@@ -54,4 +57,29 @@
       generic-extlinux-compatible.enable = true;
     };
   };
+
+  nixpkgs.overlays = [
+    (final: prev: {
+      qemu = prev.qemu.override { rutabagaSupport = false; };
+
+      uboot-custom = prev.ubootQemuRiscv64Smode.override {
+        # Override preboot to set 'bootcmd' directly to the kernel address in RAM
+        extraConfig = ''
+          CONFIG_PREBOOT="setenv fdt_addr ''${fdtcontroladdr}; fdt addr ''${fdtcontroladdr}; setenv bootcmd booti ''${kernel_addr_r} - ''${fdtcontroladdr};"
+          CONFIG_RISCV_ISA_C=n
+        '';
+        # Also include debug u-boot
+        filesToInstall = ["u-boot.bin" "u-boot"];
+      };
+
+      opensbi-uboot = prev.opensbi.overrideAttrs (old: {
+        makeFlags = old.makeFlags ++ [
+            # Build OpenSBI without compressed instructions
+            "PLATFORM_RISCV_ISA=rv64g"
+            # Check with: riscv64-unknown-elf-objdump -d -M no-aliases rotate
+            "FW_PAYLOAD_PATH=${final.uboot-custom}/u-boot.bin"
+        ];
+      });
+    })
+  ];
 }