The following commit has been merged into the x86/kconfig branch of tip:

Commit-ID:     53bc35f2d93704ccc012fcbc2039cd72f7942e94
Gitweb:        https://git.kernel.org/tip/53bc35f2d93704ccc012fcbc2039cd72f7942e94
Author:        Ingo Molnar <mingo@kernel.org>
AuthorDate:    Thu, 15 May 2025 15:27:16 +02:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 13 Jun 2025 10:03:25 +02:00

x86/kconfig/64: Enable popular kernel debugging options in the defconfig

Since the x86 defconfig aims to be a distro kernel work-alike with
fewer drivers and a shorter build time, enable a handful of
kernel debugging options that are typically enabled on major Linux
distributions.

The options enabled is a superset of the latest Ubuntu and Fedora
kernel debugging configs, using Ubuntu's config-6.11.0-24-generic
file, Fedora's kernel-x86_64-fedora.config and RHEL's
kernel-x86_64-rhel.config from kernel-ark.git.

Notable features enabled:

 - CONFIG_UBSAN=y:

     Despite the runtime overhead, UBSAN is actively enabled
     in all 3 major Linux distros I checked, so we want it
     enabled in the defconfig as well - to better see the
     consequences.

 - CONFIG_DEBUG_SHIRQ=y:

     Fedora/RHEL have this enabled, while Ubuntu has it disabled.

 - CONFIG_LIST_HARDENED=y:

     Fedora/RHEL have CONFIG_DEBUG_LIST enabled, while Ubuntu has
     it disabled, so pick the lightweight LIST_HARDENED variant.

 - CONFIG_FUNCTION_PROFILER=y:

     This is enabled on all distros I checked as well.

DEBUGINFO is still disabled, despite enabled in all Linux distros,
because the ~10x .o bloat is still just so painful on anything
but the most powerful build boxes.

Note that while the following features seemingly get removed from
the defconfig :

  - CONFIG_BLK_DEV_INITRD=y
  - CONFIG_KPROBES=y
  - CONFIG_MAGIC_SYSRQ=y

they are actually still enabled in the actual .config, because they
get selected by other options indirectly.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ivan Shapovalov <intelfx@intelfx.name>
Cc: Jürgen Groß <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20250515132719.31868-11-mingo@kernel.org
---
 arch/x86/configs/x86_64_defconfig | 46 ++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 3 deletions(-)

diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig
index 0529678..4bd3122 100644
--- a/arch/x86/configs/x86_64_defconfig
+++ b/arch/x86/configs/x86_64_defconfig
@@ -31,7 +31,6 @@ CONFIG_CGROUP_PERF=y
 CONFIG_CGROUP_BPF=y
 CONFIG_CGROUP_MISC=y
 CONFIG_CGROUP_DEBUG=y
-CONFIG_BLK_DEV_INITRD=y
 CONFIG_KALLSYMS_ALL=y
 CONFIG_PROFILING=y
 CONFIG_KEXEC=y
@@ -68,7 +67,6 @@ CONFIG_KVM_INTEL=y
 CONFIG_KVM_AMD=y
 CONFIG_KVM_XEN=y
 CONFIG_KVM_MAX_NR_VCPUS=4096
-CONFIG_KPROBES=y
 CONFIG_JUMP_LABEL=y
 CONFIG_MODULES=y
 CONFIG_MODULE_UNLOAD=y
@@ -302,14 +300,56 @@ CONFIG_SECURITY=y
 CONFIG_SECURITY_NETWORK=y
 CONFIG_SECURITY_SELINUX=y
 CONFIG_SECURITY_SELINUX_BOOTPARAM=y
+CONFIG_LIST_HARDENED=y
 CONFIG_PRINTK_TIME=y
+CONFIG_BOOT_PRINTK_DELAY=y
+CONFIG_DYNAMIC_DEBUG=y
 CONFIG_DEBUG_KERNEL=y
-CONFIG_MAGIC_SYSRQ=y
+CONFIG_STRIP_ASM_SYMS=y
+CONFIG_HEADERS_INSTALL=y
+CONFIG_DEBUG_SECTION_MISMATCH=y
+CONFIG_KGDB=y
+CONFIG_KGDB_TESTS=y
+CONFIG_KGDB_LOW_LEVEL_TRAP=y
+CONFIG_KGDB_KDB=y
+CONFIG_KDB_KEYBOARD=y
+CONFIG_UBSAN=y
+CONFIG_UBSAN_SHIFT=y
+CONFIG_PAGE_OWNER=y
+CONFIG_PAGE_POISONING=y
 CONFIG_DEBUG_WX=y
+CONFIG_PER_VMA_LOCK_STATS=y
 CONFIG_DEBUG_STACK_USAGE=y
+CONFIG_SCHED_STACK_END_CHECK=y
+CONFIG_KFENCE=y
+CONFIG_DEBUG_SHIRQ=y
+CONFIG_PANIC_ON_OOPS=y
+CONFIG_HARDLOCKUP_DETECTOR=y
+CONFIG_BOOTPARAM_HARDLOCKUP_PANIC=y
+CONFIG_WQ_CPU_INTENSIVE_REPORT=y
 CONFIG_SCHEDSTATS=y
+CONFIG_NMI_CHECK_CPU=y
+CONFIG_RCU_CPU_STALL_CPUTIME=y
+CONFIG_BOOTTIME_TRACING=y
+CONFIG_FUNCTION_GRAPH_RETVAL=y
+CONFIG_FPROBE=y
+CONFIG_FUNCTION_PROFILER=y
+CONFIG_STACK_TRACER=y
+CONFIG_SCHED_TRACER=y
+CONFIG_HWLAT_TRACER=y
+CONFIG_TIMERLAT_TRACER=y
+CONFIG_MMIOTRACE=y
+CONFIG_FTRACE_SYSCALLS=y
 CONFIG_BLK_DEV_IO_TRACE=y
+CONFIG_USER_EVENTS=y
+CONFIG_HIST_TRIGGERS=y
+CONFIG_TRACE_EVENT_INJECT=y
+CONFIG_RV=y
+CONFIG_RV_MON_WWNR=y
 CONFIG_PROVIDE_OHCI1394_DMA_INIT=y
 CONFIG_EARLY_PRINTK_DBGP=y
+CONFIG_EARLY_PRINTK_USB_XDBC=y
 CONFIG_DEBUG_BOOT_PARAMS=y
 CONFIG_DEBUG_ENTRY=y
+CONFIG_FUNCTION_ERROR_INJECTION=y
+CONFIG_MEMTEST=y