Specify consoles when booting linux kernel

This lets us take advantage of the initialization for the underlying
console device that the kernel will do so that we can just do our normal
termios setup from there.

boards/fizz-fizz/config.nix

@@ -3,6 +3,7 @@
   network = true;
   chromebook = true;
   linux = {
+    consoles = [ "ttyS0,115200n8" ];
     kconfig = with lib.kernel; {
       NET_VENDOR_REALTEK = yes;
       R8169 = yes;

boards/qemu-x86_64/config.nix

@@ -1,14 +1,17 @@
-{ lib, ... }:
+{ config, lib, ... }:
 {
   platform.qemu = true;
   network = true;
-  video = true;
   debug = true;
-  linux.kconfig = with lib.kernel; {
-    FB_VESA = yes;
-    FB_VGA16 = yes;
-    VGA_ARB = yes;
-  };
+  linux.consoles = [ "ttyS0,115200n8" ];
+  linux.kconfig = lib.mkIf config.video (
+    with lib.kernel;
+    {
+      FB_VESA = yes;
+      FB_VGA16 = yes;
+      VGA_ARB = yes;
+    }
+  );
   coreboot.kconfig = with lib.kernel; {
     BOARD_EMULATION_QEMU_X86_Q35 = yes;
     VENDOR_EMULATION = yes;

boards/volteer-elemi/config.nix

@@ -1,9 +1,9 @@
 { lib, ... }:
 {
-  debug = true;
   platform.tigerlake = true;
   chromebook = true;
   video = true;
+  linux.consoles = [ "ttyS0,115200n8" ];
   coreboot = {
     # start=0x01800000 length=0x00800000 (upper 1/4)
     wpRange.start = "0x01800000";

kernel-configs/generic.nix

@@ -77,7 +77,6 @@ in
     NLS = yes;
     NLS_CODEPAGE_437 = yes;
     NLS_ISO8859_1 = yes;
-    NULL_TTY = yes;
     PCI = yes;
     PINCTRL = yes;
     PRINTK = yes;

kernel-configs/video.nix

@@ -5,9 +5,9 @@
   ...
 }:
 {
-  linux.kconfig = lib.mkIf config.video (
-    with lib.kernel;
-    {
+  linux = lib.mkIf config.video {
+    consoles = [ "tty0" ];
+    kconfig = with lib.kernel; {
       BACKLIGHT_CLASS_DEVICE = yes;
       DRM = yes;
       DRM_SIMPLEDRM = yes;
@@ -22,6 +22,6 @@
       GOOGLE_FRAMEBUFFER_COREBOOT = yes;
       LOGO = yes;
       LOGO_LINUX_VGA16 = yes;
-    }
-  );
+    };
+  };
 }

options.nix

@@ -144,6 +144,10 @@ in
         type = types.package;
         default = pkgs.linux_latest;
       };
+      consoles = mkOption {
+        type = types.listOf types.str;
+        default = [ ];
+      };
       kconfig = kconfigOption;
       dtb = mkOption {
         type = types.nullOr types.path;
@@ -217,10 +221,8 @@ in
     linux.kconfig.CMDLINE = lib.kernel.freeform (
       toString (
         lib.optionals config.video [ "fbcon=logo-count:1" ]
-        ++ [
-          "console=ttynull"
-          "loglevel=${if config.debug then "7" else "6"}"
-        ]
+        ++ [ (if config.debug then "debug" else "quiet") ]
+        ++ map (c: "console=${c}") config.linux.consoles
       )
     );
     extraInitrdContents = lib.optional (config.linux.firmware != [ ]) {