From 93936cbe145f8480959b231a164370f5914f21ed Mon Sep 17 00:00:00 2001
From: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
Date: Wed, 10 Jul 2024 11:34:40 +0200
Subject: [PATCH] Trace function graph after a page fault

---
 JOURNAL.md     | 1 +
 lagarto-ox.nix | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/JOURNAL.md b/JOURNAL.md
index 08a69fd..e61aab2 100644
--- a/JOURNAL.md
+++ b/JOURNAL.md
@@ -1113,3 +1113,4 @@ and then begins filling it, printing the progress in the output.
     written=53248K, addr=0x3f9ec00020 OK
     written=57344K, addr=0x3f9f000020 OK
 
+Let's see if we can trace the page fault.
diff --git a/lagarto-ox.nix b/lagarto-ox.nix
index faff021..5954a7a 100644
--- a/lagarto-ox.nix
+++ b/lagarto-ox.nix
@@ -88,6 +88,14 @@
 
         export PATH=${config.system.build.extraUtils}/bin
 
+        mkdir -p /sys/kernel/debug/
+        mount -t debugfs none /sys/kernel/debug/
+        td=/sys/kernel/debug/tracing
+        echo nop > $td/current_tracer
+        echo 100 > $td/max_graph_depth
+        echo do_page_fault > $td/set_graph_function
+        echo function_graph > $td/current_tracer
+
         #memtool chain $((512 * 1024))
         memtool fill $((512 * 1024 * 1024))