From b7dba89d63193a4412791715347dad176f71f944 Mon Sep 17 00:00:00 2001
From: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
Date: Wed, 10 Jul 2024 18:04:11 +0200
Subject: [PATCH] Reduce RAM to 768 MiB to avoid a memory problem

---
 JOURNAL.md     | 23 +++++++++++++++++++++++
 lagarto-ox.nix | 25 +++++++++++++------------
 ox-plic.dts    |  7 ++++---
 3 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/JOURNAL.md b/JOURNAL.md
index 84245af..1c4e949 100644
--- a/JOURNAL.md
+++ b/JOURNAL.md
@@ -1206,3 +1206,26 @@ the actual physical memory.
 
 I will try a similar test with uboot with the `mtest` command, but requires
 enabling it first.
+
+### OBSERVATION: Memory in the 0xb0000000..0xc0000000 range is bad
+
+Reproduced from U-Boot:
+
+    => mtest 0x80000000 0x90000000 0 2
+    Testing 80000000 ... 90000000:
+    Pattern FFFFFFFFFFFFFFFF  Writing...  Reading...Iteration:      2
+    Tested 2 iteration(s) with 0 errors.
+    => mtest 0x90000000 0xa0000000 0 2
+    Testing 90000000 ... a0000000:
+    Pattern FFFFFFFFFFFFFFFF  Writing...  Reading...Iteration:      2
+    Tested 2 iteration(s) with 0 errors.
+    => mtest 0xa0000000 0xb0000000 0 2
+    Testing a0000000 ... b0000000:
+    Pattern FFFFFFFFFFFFFFFF  Writing...  Reading...Iteration:      2
+    Tested 2 iteration(s) with 0 errors.
+    => mtest 0xb0000000 0xc0000000 0 2
+    Testing b0000000 ... c0000000:
+    Pattern 0000000000000000  Writing...
+
+Let's see if we can fix the boot hang by reducing the memory enough to avoid
+this bad region.
diff --git a/lagarto-ox.nix b/lagarto-ox.nix
index f9208ca..568d349 100644
--- a/lagarto-ox.nix
+++ b/lagarto-ox.nix
@@ -132,17 +132,17 @@
       ''
         echo 0 > /proc/sys/vm/compaction_proactiveness
       ''
-      +
-      # Show stacktrace on calls to the hvc_remove function.
-      ''
-        echo "Mount debugfs"
-        mkdir -p /sys/kernel/debug/
-        mount -t debugfs none /sys/kernel/debug/
-        td=/sys/kernel/debug/tracing
-        echo hvc_remove > $td/set_ftrace_filter
-        echo function > $td/current_tracer
-        echo 1 > $td/options/func_stack_trace
-      ''
+#      +
+#      # Show stacktrace on calls to the hvc_remove function.
+#      ''
+#        echo "Mount debugfs"
+#        mkdir -p /sys/kernel/debug/
+#        mount -t debugfs none /sys/kernel/debug/
+#        td=/sys/kernel/debug/tracing
+#        echo hvc_remove > $td/set_ftrace_filter
+#        echo function > $td/current_tracer
+#        echo 1 > $td/options/func_stack_trace
+#      ''
 #      FIXME: Disable sched_switch for now, as it still hangs the boot...
 #      +
 #      # Exclude the second pid, which is the kthread that will dump the trace to
@@ -288,6 +288,7 @@
       fdt set /memory@80000000  reg <0x0 0x80000000 0x0 0xc0000000>
 
       # Set kernel bootcmd options.
+      #    rdinit=/init2            boot custom init script
       # NixOS interesting options:
       #    debug1                   enable debug shell in stage 1
       #    boot.trace               enable set -x in stage 1
@@ -298,7 +299,7 @@
       #   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 tp_printk trace_buf_size=1M rdinit=/init2 init=${init}"
+      setenv bootargs "root=/dev/ram0 loglevel=7 debug rw earlycon=sbi console=hvc0 init=${init}"
 
       EOF
 
diff --git a/ox-plic.dts b/ox-plic.dts
index 3bc0e47..e7e9249 100644
--- a/ox-plic.dts
+++ b/ox-plic.dts
@@ -70,14 +70,15 @@
 	 *
 	 * [0x0_6000_0000, 0x0_7000_0000) -> DMA pool (256 MiB)
 	 * [0x0_7000_0000, 0x0_8000_0000) -> DMA pool (256 MiB)
-	 * [0x0_8000_0000, 0x0_fff0_0000) -> RAM memory (1024 MiB)
-	 * [0x0_fff0_0000, 0x1_0000_0000) -> Empty (1024 MiB)
+	 * [0x0_8000_0000, 0x0_b000_0000) -> RAM memory (768 MiB)
+	 * [0x0_b000_0000, 0x0_c000_0000) -> Broken? (256 MiB)
+	 * [0x0_c000_0000, 0x1_0000_0000) -> Empty (1024 MiB)
 	 * [0x1_0000_0000, 0x1_c000_0000) -> PMEM (3072 MiB)
 	 * [0x1_c000_0000, 0x2_8000_0000) -> Empty (3072 MiB)
 	 */
 	memory@80000000 {
 		device_type = "memory";
-		reg = <0x0 0x80000000 0x0 0x40000000>;
+		reg = <0x0 0x80000000 0x0 0x30000000>;
 	};
 	reserved-memory {
 		#address-cells = <2>; /* Starting address and size */