diff --git a/lagarto-ox.nix b/lagarto-ox.nix
index 1a1e4e6..bc494f5 100644
--- a/lagarto-ox.nix
+++ b/lagarto-ox.nix
@@ -260,9 +260,18 @@
       # Reduce memory to 3 GiB [0x80000000, 0x140000000)
       fdt set /memory@80000000  reg <0x0 0x80000000 0x0 0xc0000000>
 
-      # Set kernel options
-      setenv debugargs "debug1 trace_options=sym-addr trace_event=initcall:* tp_printk trace_buf_size=1M"
-      setenv bootargs "root=/dev/ram0 loglevel=7 debug rw earlycon=sbi boot.trace console=hvc0 \''${debugargs} init=${init}"
+      # Set kernel bootcmd options.
+      # NixOS interesting options:
+      #    debug1                   enable debug shell in stage 1
+      #    boot.trace               enable set -x in stage 1
+      #    boot.tracedebug          enable set -x in stage 2
+      # Ftrace interesting options:
+      #   trace_event=initcall:*    trace the init function of drivers
+      #   trace_options=sym-addr    display function address
+      #   tp_printk                 write ftrace events to console
+      #   trace_buf_size=1M         set ftrace buffer to 1M
+      #
+      setenv bootargs "root=/dev/ram0 loglevel=7 debug rw earlycon=sbi console=hvc0 init=${init}"
 
       EOF