From 90f20753d950f6006afc16fc9adec8947282312b Mon Sep 17 00:00:00 2001
From: domingo-nexthop <domingo@nexthop.ai>
Date: Fri, 15 May 2026 10:14:01 -0700
Subject: [PATCH] save and restore ARP, FDB for fast reboot

Signed-off-by: domingo-nexthop <domingo@nexthop.ai>
---
 scripts/fast-reboot | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/scripts/fast-reboot b/scripts/fast-reboot
index 33fa9f89875..27d4201684a 100755
--- a/scripts/fast-reboot
+++ b/scripts/fast-reboot
@@ -35,6 +35,9 @@ LOG_PATH="/var/log/${REBOOT_TYPE}.txt"
 UIMAGE_HDR_SIZE=64
 REQUIRE_TEAMD_RETRY_COUNT=no
 
+FAST_BOOT_DIR=/host/fast-reboot
+FAST_REBOOT_DUMP=/usr/local/bin/fast-reboot-dump.py
+
 EXIT_SUCCESS=0
 EXIT_FAILURE=1
 EXIT_NOT_SUPPORTED=2
@@ -503,6 +506,25 @@ function backup_database()
     fi
 }
 
+function dump_state_for_fast_boot()
+{
+    if [[ ! -x "$FAST_REBOOT_DUMP" ]]; then
+        debug "$FAST_REBOOT_DUMP not found; skipping fast-boot state dump"
+        return
+    fi
+    if [[ $NUM_ASIC -gt 1 ]]; then
+        debug "Multi-ASIC: skipping fast-boot state dump (unsupported)"
+        return
+    fi
+    rm -rf "$FAST_BOOT_DIR"
+    mkdir -p "$FAST_BOOT_DIR"
+    debug "Dumping FDB/ARP/route/serdes state to $FAST_BOOT_DIR ..."
+    if ! "$FAST_REBOOT_DUMP" -t "$FAST_BOOT_DIR"; then
+        debug "fast-reboot-dump.py exited $? — cleaning up $FAST_BOOT_DIR and continuing"
+        rm -rf "$FAST_BOOT_DIR"
+    fi
+}
+
 function check_mirror_session_acls()
 {
     debug "Checking if mirror session ACLs (arp, nd) programmed to ASIC successfully"
@@ -1131,6 +1153,9 @@ if [[ "${REBOOT_TYPE}" = "warm-reboot" || "${REBOOT_TYPE}" = "fastfast-reboot" |
     execute_in_namespaces asic increase_teamd_retry_count
 fi
 
+if [[ "$REBOOT_TYPE" = "fast-reboot" ]]; then
+    dump_state_for_fast_boot
+fi
 
 # We are fully committed to reboot from this point on because critical
 # service will go down and we cannot recover from it.