1 files changed, 77 insertions, 0 deletions
diff --git a/nixos/modules/misc/crashdump.nix b/nixos/modules/misc/crashdump.nix
new file mode 100644
index 00000000000..6e6bc9dec0f
--- /dev/null
+++ b/nixos/modules/misc/crashdump.nix
@@ -0,0 +1,77 @@
+{pkgs, config, ...}:
+
+with pkgs.lib;
+
+let
+  crashdump = config.boot.crashDump;
+
+  kernelParams = concatStringsSep " " crashdump.kernelParams;
+
+in
+###### interface
+{
+  options = {
+    boot = {
+      crashDump = {
+        enable = mkOption {
+          default = false;
+          example = true;
+          description = ''
+            If enabled, NixOS will set up a kernel that will
+            boot on crash, and leave the user to a stage1 debug1devices
+            interactive shell to be able to save the crashed kernel dump.
+            It also activates the NMI watchdog.
+          '';
+        };
+        kernelPackages = mkOption {
+          default = pkgs.linuxPackages;
+          # We don't want to evaluate all of linuxPackages for the manual
+          # - some of it might not even evaluate correctly.
+          defaultText = "pkgs.linuxPackages";
+          example = "pkgs.linuxPackages_2_6_25";
+          description = ''
+            This will override the boot.kernelPackages, and will add some
+            kernel configuration parameters for the crash dump to work.
+          '';
+        };
+        kernelParams = mkOption {
+          default = [ "debug1devices" ];
+          description = ''
+            Parameters that will be passed to the kernel kexec-ed on crash.
+          '';
+        };
+      };
+    };
+  };
+
+###### implementation
+
+  config = mkIf crashdump.enable {
+    boot = {
+      postBootCommands = ''
+        ${pkgs.kexectools}/sbin/kexec -p /run/current-system/kernel \
+        --initrd=/run/current-system/initrd \
+        --append="init=$(readlink -f /run/current-system/init) system=$(readlink -f /run/current-system) irqpoll maxcpus=1 reset_devices ${kernelParams}" --reset-vga --console-vga
+      '';
+      kernelParams = [
+       "crashkernel=64M"
+       "nmi_watchdog=panic"
+       "softlockup_panic=1"
+       "idle=poll"
+      ];
+      kernelPackages = mkOverride 50 (crashdump.kernelPackages // {
+        kernel = crashdump.kernelPackages.kernel.override 
+          (attrs: {
+            extraConfig = (optionalString (attrs ? extraConfig) attrs.extraConfig) +
+              ''
+                CRASH_DUMP y
+                DEBUG_INFO y
+                PROC_VMCORE y
+                LOCKUP_DETECTOR y
+                HARDLOCKUP_DETECTOR y
+              '';
+          });
+      });
+    };
+  };
+}