diff --git a/NEWS.adoc b/NEWS.adoc
index d208096758..4876dab631 100644
--- a/NEWS.adoc
+++ b/NEWS.adoc
@@ -82,6 +82,11 @@ https://github.com/networkupstools/nut/milestone/10
      building NUT without it. [#2262]
    * Builds requested with a specific C/C++ language standard revision via
      `CFLAGS` and `CXXFLAGS` should again be honoured. [PR #2306]
+   * Allow requesting detailed debug builds (with disabled optimizations for
+     binaries to best match the source code) for supported compilers using
+     `configure` script option `--with-debuginfo`. Note that default autoconf
+     behavior usually embeds moderate optimizations and debug information on
+     its own. [PR #2310]
 
  - nut-usbinfo.pl, nut-scanner and libnutscan:
    * Library API version for `libnutscan` was bumped from 2.2.0 to 2.5.0
diff --git a/ci_build.sh b/ci_build.sh
index f6491d4373..2e6dc3bd2c 100755
--- a/ci_build.sh
+++ b/ci_build.sh
@@ -96,6 +96,9 @@ if [ "$BUILD_TYPE" = fightwarn ]; then
     #[ -n "$NUT_USB_VARIANTS" ] || NUT_USB_VARIANTS=auto
 fi
 
+# configure default is "no"; an "auto" value is "yes unless CFLAGS say something"
+[ -n "${BUILD_DEBUGINFO-}" ] || BUILD_DEBUGINFO=""
+
 # Set this to enable verbose profiling
 [ -n "${CI_TIME-}" ] || CI_TIME=""
 case "$CI_TIME" in
@@ -1299,6 +1302,10 @@ default|default-alldrv|default-alldrv:no-distcheck|default-all-errors|default-sp
     # and errors are found more easily in a wall of text:
     CONFIG_OPTS+=("--enable-Wcolor")
 
+    if [ -n "${BUILD_DEBUGINFO-}" ]; then
+        CONFIG_OPTS+=("--with-debuginfo=${BUILD_DEBUGINFO}")
+    fi
+
     # Note: modern auto(re)conf requires pkg-config to generate the configure
     # script, so to stage the situation of building without one (as if on an
     # older system) we have to remove it when we already have the script.
@@ -1317,6 +1324,15 @@ default|default-alldrv|default-alldrv:no-distcheck|default-all-errors|default-sp
         fi
     fi
 
+    # When itertating configure.ac or m4 sources, we can end up with an
+    # existing but useless scropt file - nuke it and restart from scratch!
+    if [ -s "${CI_BUILDDIR}"/configure ] ; then
+        if ! sh -n "${CI_BUILDDIR}"/configure 2>/dev/null ; then
+            echo "=== Starting initial clean-up (from old build products): TAKING SHORTCUT because current configure script syntax is broken"
+            rm -f "${CI_BUILDDIR}"/Makefile "${CI_BUILDDIR}"/configure
+        fi
+    fi
+
     if [ -s Makefile ]; then
         # Let initial clean-up be at default verbosity
 
@@ -1893,7 +1909,7 @@ bindings)
     pushd "./bindings/${BINDING}" && ./ci_build.sh
     ;;
 ""|inplace)
-    echo "ERROR: No BUILD_TYPE was specified, doing a minimal default ritual without any required options" >&2
+    echo "WARNING: No BUILD_TYPE was specified, doing a minimal default ritual without any *required* build products and with developer-oriented options" >&2
     if [ -n "${BUILD_WARNOPT}${BUILD_WARNFATAL}" ]; then
         echo "WARNING: BUILD_WARNOPT and BUILD_WARNFATAL settings are ignored in this mode (warnings are always enabled and fatal for these developer-oriented builds)" >&2
         sleep 5
@@ -1925,6 +1941,15 @@ bindings)
         fi
     fi
 
+    # When itertating configure.ac or m4 sources, we can end up with an
+    # existing but useless scropt file - nuke it and restart from scratch!
+    if [ -s "${CI_BUILDDIR}"/configure ] ; then
+        if ! sh -n "${CI_BUILDDIR}"/configure 2>/dev/null ; then
+            echo "=== Starting initial clean-up (from old build products): TAKING SHORTCUT because current configure script syntax is broken"
+            rm -f "${CI_BUILDDIR}"/Makefile "${CI_BUILDDIR}"/configure
+        fi
+    fi
+
     if [ -s Makefile ]; then
         # Help developers debug:
         # Let initial clean-up be at default verbosity
@@ -1958,6 +1983,12 @@ bindings)
         CONFIG_OPTS+=("--disable-silent-rules")
     fi
 
+    if [ -n "${BUILD_DEBUGINFO-}" ]; then
+        CONFIG_OPTS+=("--with-debuginfo=${BUILD_DEBUGINFO}")
+    else
+        CONFIG_OPTS+=("--with-debuginfo=auto")
+    fi
+
     ${CONFIGURE_SCRIPT} "${CONFIG_OPTS[@]}"
 
     # NOTE: Currently parallel builds are expected to succeed (as far
diff --git a/configure.ac b/configure.ac
index 83b5b2a0be..45f4ebcb88 100644
--- a/configure.ac
+++ b/configure.ac
@@ -103,6 +103,18 @@ If this happens, please retry with GNU C/C++ language mode options instead.
 		])]
 )
 
+dnl +-------------------------------------------------------------------
+dnl Help avoid "polluting" CFLAGS etc. with auto-settings like "-g -O2"
+dnl at least if we intend to tune --with-debuginfo anyway (where we check
+dnl if the caller asked for specific optimizations). Following some
+dnl experimentation, we do not want to actually mangle the flags provided
+dnl by autoconf - for GCC at least, the rightmost mentions of conflicting
+dnl flags on command line win. We just want to know when it is okay to add
+dnl ours. They may be inherited from "in-place" build setup though.
+test -n "${CONFIG_CFLAGS-}" || CONFIG_CFLAGS="${CFLAGS-}"
+test -n "${CONFIG_CXXFLAGS-}" || CONFIG_CXXFLAGS="${CXXFLAGS-}"
+dnl +-------------------------------------------------------------------
+
 dnl Default to `configure --enable-silent-rules` or `make V=1` for details?
 dnl This feature seems to require automake-1.13 or newer (1.11+ by other info)
 dnl On very old systems can comment it away with little loss (then automake-1.10
@@ -110,21 +122,49 @@ dnl is known to suffice):
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])],
 	[AC_MSG_NOTICE([Silent Rules feature not defined in this automake version, skipped])])
 
+dnl +-------------------------------------------------------------------
 dnl we need Autoconf 2.61 or better to enable features of Posix that are extensions to C
 dnl (and actually 2.64 or better for m4/ax_check_compile_flag.m4 when it is sourced)
 dnl UPDATE: As tested on CentOS 6, its "autoconf-2.63-5.1.el6.noarch" also suffices.
 dnl But OpenBSD 6.5 requires autoconf-2.65 and automake-1.13 or newer...
+dnl AC_MSG_NOTICE([CFLAGS_BEFORE_ACPROG="${CFLAGS-}"])
+dnl AC_MSG_NOTICE([CXXFLAGS_BEFORE_ACPROG="${CXXFLAGS-}"])
 AC_MSG_CHECKING(for autoconf macro to enable system extensions)
 m4_version_prereq(2.61, [
 	AC_MSG_RESULT(yes)
+        dnl Causes calls to ac_prog stuff, so dittoed below if "no"
 	AC_USE_SYSTEM_EXTENSIONS
 ], [
 	AC_MSG_RESULT(no)
+	AC_PROG_CC
 ])
 
 AC_PREREQ([2.63])
 dnl #AC_PREREQ([2.64])
 
+dnl Macro AC_PROG_CC_C99 is obsolete; use AC_PROG_CC
+dnl Note that NUT does not support building with C89 anyway
+dnl AC_PROG_CC_C99
+dnl Needed for per-target flags
+AM_PROG_CC_C_O
+AC_PROG_CPP
+AC_PROG_CXX
+AC_PROG_CXX_C_O
+
+CFLAGS_AFTER_ACPROG="${CFLAGS-}"
+CXXFLAGS_AFTER_ACPROG="${CXXFLAGS-}"
+
+dnl AC_MSG_NOTICE([CFLAGS_AFTER_ACPROG="${CFLAGS-}"])
+dnl AC_MSG_NOTICE([CXXFLAGS_AFTER_ACPROG="${CXXFLAGS-}"])
+
+dnl # LEGACY DEFAULT FALLBACK which NUT had since 2005 or before:
+dnl # if autoconf does not set any options, use default/moderate optimizations
+CFLAGS=${CFLAGS-"-O"}
+dnl # Not so far a legacy, added for consistency in 2024 :)
+CXXFLAGS=${CXXFLAGS-"-O"}
+
+dnl +-------------------------------------------------------------------
+
 dnl Use "./configure --enable-maintainer-mode" to keep Makefile.in and Makefile
 dnl in sync after Git updates.
 AM_MAINTAINER_MODE
@@ -171,8 +211,6 @@ dnl Fix this early so we can expand with eval later
 test "${prefix}" = "NONE" && prefix="${ac_default_prefix}"
 test "${exec_prefix}" = "NONE" && exec_prefix='${prefix}'
 
-CFLAGS=${CFLAGS-"-O"}
-
 dnl Note: for practical and platform-independent use, see AX_REALPATH macro
 AC_CHECK_PROGS([REALPATH], [realpath], [])
 
@@ -574,11 +612,21 @@ AS_IF([test x"$nut_enable_inplace_runtime" = xyes -a x"${NUT_VERSION_DEPLOYED-}"
             NUT_VERSION_DEPLOYED="<reenter>"
         ])
         export NUT_VERSION_DEPLOYED
+        dnl # Avoid replacement after re-entering:
+        test -n "${CONFIG_CFLAGS-}" || CONFIG_CFLAGS=" "
+        test -n "${CONFIG_CXXFLAGS-}" || CONFIG_CXXFLAGS=" "
+        export CONFIG_CFLAGS
+        export CONFIG_CXXFLAGS
         eval exec "$0" $CONFIG_FLAGS_DEPLOYED $CONFIG_FLAGS --disable-inplace-runtime
     ],[
         AC_MSG_NOTICE([No CONFIG_FLAGS were reported or discovered from existing NUT deployment (if any); restarting script for a clean run])
         NUT_VERSION_DEPLOYED="<reenter>"
         export NUT_VERSION_DEPLOYED
+        dnl # Avoid replacement after re-entering:
+        test -n "${CONFIG_CFLAGS-}" || CONFIG_CFLAGS=" "
+        test -n "${CONFIG_CXXFLAGS-}" || CONFIG_CXXFLAGS=" "
+        export CONFIG_CFLAGS
+        export CONFIG_CXXFLAGS
         AC_MSG_NOTICE([exec "$0" $CONFIG_FLAGS --disable-inplace-runtime])
         eval exec "$0" $CONFIG_FLAGS --disable-inplace-runtime
     ])
@@ -589,15 +637,6 @@ AC_CONFIG_LIBOBJ_DIR([common])
 
 dnl +-------------------------------------------------------------------
 
-dnl AC_PROG_CC
-dnl Macro AC_PROG_CC_C99 is obsolete; use AC_PROG_CC
-dnl Note that NUT does not support building with C89 anyway
-dnl AC_PROG_CC_C99
-dnl Needed for per-target flags
-AM_PROG_CC_C_O
-AC_PROG_CPP
-AC_PROG_CXX
-AC_PROG_CXX_C_O
 AC_PROG_INSTALL
 AC_PROG_MKDIR_P
 AC_PROG_LN_S
@@ -1609,7 +1648,7 @@ AC_ARG_WITH(all,
 			dnl # if test -z "${with_nut_monitor}"; then with_nut_monitor="${withval}"; fi
 		fi
 
-		AC_MSG_RESULT("${withval}")
+		AC_MSG_RESULT([${withval}])
 	else
 		AC_MSG_RESULT(not given)
 	fi
@@ -1653,6 +1692,9 @@ NUT_ARG_ENABLE([warnings],
 NUT_ARG_ENABLE([Werror],
     [fail the build if compiler emits any warnings (treat them as errors)],
     [no])
+NUT_ARG_WITH([debuginfo],
+    [enable compiler options for debug-friendly builds of all NUT binaries ("no" by default; "auto" means "yes unless CFLAGS say otherwise")],
+    [no])
 dnl To help find warning/error details in a wall of text, see --enable-Wcolor handled above
 
 dnl ----------------------------------------------------------------------
@@ -3573,6 +3615,9 @@ unset CPLUSPLUS_DECL
 
 AC_MSG_CHECKING(for have_cppunit)
 have_cppunit="no"
+dnl CPPUNIT_NUT_CXXFLAGS are set below if suitable, but can be
+dnl disabled further below if nut_with_debuginfo gets applied
+dnl for all NUT build products:
 CPPUNIT_NUT_CXXFLAGS=""
 AS_IF([test x"$have_PKG_CONFIG" = xyes],
     [AS_IF([test x"${have_cxx11}" = xyes],
@@ -3656,16 +3701,20 @@ return res ? 0 : 1;
 dnl # By default keep the originally detected have_cppunit value
 AC_MSG_CHECKING(for impact from --enable-cppunit option - should we build cppunit tests?)
 AC_ARG_ENABLE(cppunit,
-	[AS_HELP_STRING([--enable-cppunit], [enable CPPUNIT tests for C++ bindings])],
+	[AS_HELP_STRING([--enable-cppunit], [enable CPPUNIT tests for C++ bindings (yes, no, force, auto)])],
 	[AS_CASE(["${enableval}"],
-		["yes"], [AS_IF([test x"${have_cppunit}" = xyes], [], [AC_MSG_ERROR([--with-cppunit=yes can not be satisfied])])],
+		["force"], [AS_IF([test x"${have_cppunit}" = xyes], [], [
+			AC_MSG_WARN([--enable-cppunit=yes can not be satisfied, but developer asked for it])
+			have_cppunit=yes
+			])],
+		["yes"], [AS_IF([test x"${have_cppunit}" = xyes], [], [AC_MSG_ERROR([--enable-cppunit=yes can not be satisfied])])],
 		["no"], [have_cppunit=no]
+		dnl # "auto" and other values keep what was detected (or not)
 	)])
 AC_MSG_RESULT(${have_cppunit})
 
 NUT_REPORT_FEATURE([build C++ tests with CPPUNIT], [${have_cppunit}], [],
 					[HAVE_CPPUNIT], [Define to enable CPPUNIT tests])
-AC_DEFINE_UNQUOTED(CPPUNIT_NUT_CXXFLAGS, $CPPUNIT_NUT_CXXFLAGS, [Compiler flags for cppunit tests])
 
 AC_MSG_CHECKING(whether to install Augeas configuration-management lenses)
 AC_ARG_WITH(augeas-lenses-dir,
@@ -4286,7 +4335,7 @@ AS_CASE(["${nut_enable_warnings}"],
      nut_enable_warnings="no"
     ]
 )
-AC_MSG_RESULT(["${nut_enable_warnings}"])
+AC_MSG_RESULT([${nut_enable_warnings}])
 
 dnl # Nothing special for gcc - we tend to survive it with GNU standard >= 99
 dnl # and fail with strict C standard. Suggestions welcome for "gcc-hard" to
@@ -4422,7 +4471,7 @@ AS_CASE(["${nut_enable_Werror}"],
         CXXFLAGS="${CXXFLAGS} -Wno-error"
         ]
 )
-AC_MSG_RESULT(["${nut_enable_Werror}"])
+AC_MSG_RESULT([${nut_enable_Werror}])
 
 dnl Some compilers (e.g. older clang-3.4) have issues with built-in methods
 dnl that are implemented as macros in system headers -- but only for some
@@ -4554,7 +4603,8 @@ AS_IF([test -n "${ac_abs_top_builddir}" && test -d "${ac_abs_top_builddir}"],
          TOP_BUILDDIR="`cd "$TOP_BUILDDIR" && pwd`" || AC_MSG_ERROR([Can not detect TOP_BUILDDIR])]
     )]
 )
-AC_MSG_RESULT(["${TOP_BUILDDIR}"])
+dnl Quoted in case someone copy-pastes this path and it has whitespaces:
+AC_MSG_RESULT(['${TOP_BUILDDIR}'])
 
 ABS_TOP_BUILDDIR="`cd "${TOP_BUILDDIR}" && pwd`" || AC_MSG_ERROR([Can not detect ABS_TOP_BUILDDIR])
 ABS_TOP_SRCDIR="`cd "${abs_srcdir}" && pwd`" || AC_MSG_ERROR([Can not detect ABS_TOP_SRCDIR])
@@ -4658,6 +4708,68 @@ AC_ARG_VAR(CCACHE_PATH)
 PATH_DURING_CONFIGURE="$PATH"
 AC_SUBST(PATH_DURING_CONFIGURE)
 
+dnl Some binaries, like CPPUNIT tests, have similar flags already added
+dnl We might wipe their specific options below if consistently applying
+dnl debug-friendly options to everything
+AC_MSG_NOTICE([CONFIG_CFLAGS='${CONFIG_CFLAGS}'])
+AC_MSG_NOTICE([CONFIG_CXXFLAGS='${CONFIG_CXXFLAGS}'])
+AC_MSG_CHECKING([whether to enable debug info in all NUT binaries])
+nut_with_debuginfo_C="${nut_with_debuginfo}"
+nut_with_debuginfo_CXX="${nut_with_debuginfo}"
+AS_CASE(["${CONFIG_CFLAGS}"],
+    [*-O*|*-g*], [
+        AS_IF([test x"${nut_with_debuginfo_C}" = xauto], [
+            nut_with_debuginfo_C="Related settings already specified by caller CFLAGS, not changing anything"
+            ])
+        ],
+    [   dnl No competing options are provided
+        AS_IF([test x"${nut_with_debuginfo_C}" = xauto], [nut_with_debuginfo_C="yes"])
+    ])
+
+AS_CASE(["${CONFIG_CXXFLAGS}"],
+    [*-O*|*-g*], [
+        AS_IF([test x"${nut_with_debuginfo_CXX}" = xauto], [
+            nut_with_debuginfo_CXX="Related settings already specified by caller CXXFLAGS, not changing anything"
+            ])
+        ],
+    [   dnl No competing options are provided
+        AS_IF([test x"${nut_with_debuginfo_CXX}" = xauto], [nut_with_debuginfo_CXX="yes"])
+    ])
+
+AS_CASE(["${nut_with_debuginfo_C}"],
+    [yes], [
+        AS_IF([test x"${CLANGCC}" = x"yes" -o x"${GCC}" = x"yes"], [
+            CFLAGS="${CFLAGS} -O0 -g3 -gdwarf-2"
+            ],[nut_with_debuginfo_C="Unknown C compiler, not adding options"]
+        )],
+    dnl # [no]: By default we do not add debug info
+    [legacy], [
+        dnl # Apply legacy defaults if no flags were specified by caller or detected by autoconf
+        AS_IF([test x"${CFLAGS_AFTER_ACPROG}" = x],	[CFLAGS="-O ${CFLAGS}"])
+        ]
+)
+
+AS_CASE(["${nut_with_debuginfo_CXX}"],
+    [yes], [
+        AS_IF([test "x$CLANGXX" = xyes -o "x$GXX" = xyes], [
+            dnl Where we can enable debug, minimize the optimizations
+            CXXFLAGS="${CXXFLAGS} -O0 -g3 -gdwarf-2"
+            dnl Use same settings for CPPUNIT tests (they bump their own by default)
+            CPPUNIT_NUT_CXXFLAGS=""
+            ],[nut_with_debuginfo_CXX="Unknown C++ compiler, not adding options"]
+        )],
+    dnl # [no]: By default we do not add debug info
+    [legacy], [
+        dnl # Apply legacy defaults if no flags were specified by caller or detected by autoconf
+        AS_IF([test x"${CXXFLAGS_AFTER_ACPROG}" = x],	[CXXFLAGS="-O ${CXXFLAGS}"])
+        ]
+)
+
+AC_MSG_RESULT([C: ${nut_with_debuginfo_C}; C++: ${nut_with_debuginfo_CXX}])
+
+dnl Only in the end, do you understand...
+AC_SUBST(CPPUNIT_NUT_CXXFLAGS)
+
 AC_MSG_NOTICE([Generating "data" files from templates, see below for executable scripts])
 AC_CONFIG_FILES([
  clients/Makefile
diff --git a/docs/nut.dict b/docs/nut.dict
index b4b6c3b31a..f0feecc9c9 100644
--- a/docs/nut.dict
+++ b/docs/nut.dict
@@ -1,4 +1,4 @@
-personal_ws-1.1 en 3444 utf-8
+personal_ws-1.1 en 3446 utf-8
 AAC
 AAS
 ABI
@@ -1896,6 +1896,7 @@ dataok
 datasheet
 datastale
 dayofweek
+dbgsym
 dblatex
 dcd
 dcn
@@ -1906,6 +1907,7 @@ deUNV
 debian
 debootstrap
 debouncing
+debuginfo
 deci
 decrement
 decrypt
diff --git a/m4/nut_report_feature.m4 b/m4/nut_report_feature.m4
index dd2666cd58..02ff814033 100644
--- a/m4/nut_report_feature.m4
+++ b/m4/nut_report_feature.m4
@@ -129,6 +129,23 @@ AC_DEFUN([NUT_REPORT_COMPILERS],
      echo "NUT Compiler settings:"
      echo "----------------------"
      echo ""
+     if test x"${nut_with_debuginfo_C}" = x"yes" -o x"${nut_with_debuginfo_CXX}" = x"yes" ; then
+        printf 'NOTE: Settings for '
+        if test x"${nut_with_debuginfo_C}" = x"yes" ; then
+            printf 'C '
+        fi
+        if test x"${nut_with_debuginfo_C}${nut_with_debuginfo_CXX}" = x"yesyes" ; then
+            printf 'and '
+        fi
+        if test x"${nut_with_debuginfo_CXX}" = x"yes" ; then
+            printf 'C++ '
+        fi
+        printf 'compiler'
+        if test x"${nut_with_debuginfo_C}${nut_with_debuginfo_CXX}" = x"yesyes" ; then
+            printf 's'
+        fi
+        printf ' are adjusted for debugging (and minimal optimizations)\n\n'
+     fi
      printf '* CC      \t: %s\n' "$CC"
      printf '* CFLAGS  \t: %s\n' "$CFLAGS"
      printf '* CXX     \t: %s\n' "$CXX"
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 8ddb86af43..4d825159a8 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -21,6 +21,9 @@ CLEANFILES = *.trs *.log
 AM_CFLAGS = -I$(top_srcdir)/include -I$(top_srcdir)/drivers
 AM_CXXFLAGS = -I$(top_srcdir)/include
 
+# Compiler flags for cppunit tests
+CPPUNIT_NUT_CXXFLAGS = @CPPUNIT_NUT_CXXFLAGS@
+
 check_PROGRAMS = $(TESTS)
 check_SCRIPTS =