From 102efcd3120831b6823e9ad8b0ba4628e981b3f4 Mon Sep 17 00:00:00 2001
From: Mike Yuan <me@yhndnzj.com>
Date: Tue, 15 Oct 2024 18:36:51 +0200
Subject: [PATCH] Bump kernel recommended baseline to v5.4

---
 NEWS                  | 6 ++++++
 README                | 8 ++++----
 src/basic/constants.h | 2 +-
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/NEWS b/NEWS
index 47cd6ad45dd..321750b7e11 100644
--- a/NEWS
+++ b/NEWS
@@ -47,6 +47,12 @@ CHANGES WITH 257 in spe:
           migrated between cgroups. It might be fully removed in a future release
           (reach out if you have use cases).
 
+        * The recommended kernel baseline version has been bumped to v5.4
+          (released in 2019). Expect limited testing on older kernel versions,
+          where "old-kernel" taint flag would also be set. Support for them
+          will be phased out in a future release in 2025, i.e. we expect to bump
+          the minimum baseline to v5.4 then too.
+
         * Support for cgroup v1 ('legacy' and 'hybrid' hierarchies) is now
           considered obsolete and systemd by default will refuse to boot under
           it. To forcibly reenable cgroup v1 support,
diff --git a/README b/README
index 7c7bbaf0701..9b84bf7e7ae 100644
--- a/README
+++ b/README
@@ -39,16 +39,16 @@ REQUIREMENTS:
                      ≥ 4.17 for cgroup-bpf socket address hooks
                      ≥ 4.20 for PSI (used by systemd-oomd)
                      ≥ 5.3 for bounded loops in BPF program
-                     ≥ 5.4 for signed Verity images
-                     ≥ 5.7 for BPF links and the BPF LSM hook
+                     ≥ 5.4 for pidfd and signed Verity images
+                     ≥ 5.7 for CLONE_INTO_CGROUP, BPF links and the BPF LSM hook
 
         ⛔ Kernel versions below 3.15 ("minimum baseline") are not supported at
         all, and are missing required functionality (e.g. CLOCK_BOOTTIME
         support for timerfd_create()).
 
-        ⚠️ Kernel versions below 4.15 ("recommended baseline") have significant
+        ⚠️ Kernel versions below 5.4 ("recommended baseline") have significant
         gaps in functionality and are not recommended for use with this version
-        of systemd (e.g. lack sufficiently comprehensive and working cgroupv2
+        of systemd (e.g. lack race-free process tracking by pidfd and new mount API
         support). Taint flag 'old-kernel' will be set. systemd will most likely
         still function, but upstream support and testing are limited.
 
diff --git a/src/basic/constants.h b/src/basic/constants.h
index e70817c51f8..5aaf8f535c2 100644
--- a/src/basic/constants.h
+++ b/src/basic/constants.h
@@ -85,4 +85,4 @@
 /* Path where systemd-oomd listens for varlink connections from user managers to report changes in ManagedOOM settings. */
 #define VARLINK_ADDR_PATH_MANAGED_OOM_USER "/run/systemd/oom/io.systemd.ManagedOOM"
 
-#define KERNEL_BASELINE_VERSION "4.15"
+#define KERNEL_BASELINE_VERSION "5.4"