From 8c2b28cf21d5e6c35dd8d848ac8507285a006f63 Mon Sep 17 00:00:00 2001
From: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
Date: Fri, 12 Jul 2024 10:50:28 +0200
Subject: [PATCH] Enable systemd debug log and all-in-order

---
 JOURNAL.md     |  8 ++++++++
 lagarto-ox.nix | 44 ++++++++++++++++++++------------------------
 2 files changed, 28 insertions(+), 24 deletions(-)

diff --git a/JOURNAL.md b/JOURNAL.md
index 47890ca..cb36ee4 100644
--- a/JOURNAL.md
+++ b/JOURNAL.md
@@ -1427,3 +1427,11 @@ clues by enabling the debug mode.
 
 If a trap is being issued, we may be able to modify OpenSBI to print some
 information to the serial console so we can understand what is going on.
+
+In the meanwhile, let's try a simple test. We can enable debug output of systemd
+with the following boot options:
+
+    systemd.log_level=debug systemd.log_target=console
+
+We will also need to run `csrtool all-in-order` to arrive to systemd.
+
diff --git a/lagarto-ox.nix b/lagarto-ox.nix
index d03a206..ab0ab8f 100644
--- a/lagarto-ox.nix
+++ b/lagarto-ox.nix
@@ -81,31 +81,24 @@
       kernelModules = [ ];
 
       # Custom init script
-      extraFiles."/init2".source = pkgs.writeScript "init2" ''
-        #!${config.system.build.extraUtils}/bin/ash
+      extraFiles = {
+        "/shell".source = pkgs.writeScript "shell" ''
+          #!${config.system.build.extraUtils}/bin/ash
 
-        set -x
+          set -x
 
-        export PATH=${config.system.build.extraUtils}/bin
+          export PATH=${config.system.build.extraUtils}/bin
+          ash
+        '';
 
-        #mkdir -p /tracing
-        #mount -t tracefs nodev /tracing
-
-        #cd /tracing
-        #echo nop > current_tracer
-        #echo 100 > max_graph_depth
-        #echo handle_page_fault > set_graph_function
-        #echo function_graph > current_tracer
-        #cd /
-
-        # Open an interactive shell
-        ash
-
-        memtool fill $((512 * 1024 * 1024))
-
-        # Unlikely to reach this point
-        exec /init
-      '';
+        "/preinit".source = pkgs.writeScript "preinit" ''
+          #!${config.system.build.extraUtils}/bin/ash
+          set -x
+          export PATH=${config.system.build.extraUtils}/bin
+          csrtool all-in-order
+          exec /init
+        '';
+      };
 
       # Add the csrtool to the initrd so we can change the
       # in-order/out-of-order, and memtool to stress the memory.
@@ -283,7 +276,10 @@
       fdt set /memory@80000000  reg <0x0 0x80000000 0x0 0xc0000000>
 
       # Set kernel bootcmd options.
-      #    rdinit=/init2            boot custom init script
+      #    rdinit=/preinit          boot custom preinit script
+      # Systemd options
+      #    systemd.log_level=debug
+      #    systemd.log_target=console
       # NixOS interesting options:
       #    debug1                   enable debug shell in stage 1
       #    boot.trace               enable set -x in stage 1
@@ -294,7 +290,7 @@
       #   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=${init}"
+      setenv bootargs "root=/dev/ram0 loglevel=7 debug rw earlycon=sbi console=hvc0 systemd.log_level=debug systemd.log_target=console rdinit=/preinit init=${init}"
 
       EOF