--AC_MSG_CHECKING([kernel version that we will build against])
--krel="$(make -sC "$kbuilddir" M=. kernelrelease)";
--kmajor="${krel%%[[^0-9]]*}";
--kmajor="$(($kmajor+0))";
--krel="${krel:${#kmajor}}";
--krel="${krel#.}";
--kminor="${krel%%[[^0-9]]*}";
--kminor="$(($kminor+0))";
--krel="${krel:${#kminor}}";
--krel="${krel#.}";
--kmicro="${krel%%[[^0-9]]*}";
--kmicro="$(($kmicro+0))";
--krel="${krel:${#kmicro}}";
--krel="${krel#.}";
--kstable="${krel%%[[^0-9]]*}";
--kstable="$(($kstable+0))";
--if test -z "$kmajor" -o -z "$kminor" -o -z "$kmicro"; then
-- echo "WARNING: Version detection did not succeed. Continue at own luck.";
--else
-- echo "$kmajor.$kminor.$kmicro.$kstable in $kbuilddir";
-- if test "$kmajor" -gt 2 -o "$kminor" -gt 6 -o "$kmicro" -gt 36; then
-- echo "WARNING: You are trying a newer kernel. Results may vary. :-)";
-- elif test \( "$kmajor" -lt 2 -o \
-- \( "$kmajor" -eq 2 -a "$kminor" -lt 6 \) -o \
-- \( "$kmajor" -eq 2 -a "$kminor" -eq 0 -a "$kmicro" -lt 17 \) -o \
-- \( "$kmajor" -eq 2 -a "$kminor" -eq 6 -a "$kmicro" -eq 18 -a \
-- "$kstable" -lt 5 \) \); then
-- echo "ERROR: That kernel version is not supported. Please see INSTALL for minimum configuration.";
-- exit 1;
+-if test -n "$kbuilddir"; then
+- AC_MSG_CHECKING([kernel version that we will build against])
+- krel="$(make -sC "$kbuilddir" M=. kernelrelease)";
+- kmajor="${krel%%[[^0-9]]*}";
+- kmajor="$(($kmajor+0))";
+- krel="${krel:${#kmajor}}";
+- krel="${krel#.}";
+- kminor="${krel%%[[^0-9]]*}";
+- kminor="$(($kminor+0))";
+- krel="${krel:${#kminor}}";
+- krel="${krel#.}";
+- kmicro="${krel%%[[^0-9]]*}";
+- kmicro="$(($kmicro+0))";
+- krel="${krel:${#kmicro}}";
+- krel="${krel#.}";
+- kstable="${krel%%[[^0-9]]*}";
+- kstable="$(($kstable+0))";
+- if test -z "$kmajor" -o -z "$kminor" -o -z "$kmicro"; then
+- echo "WARNING: Version detection did not succeed. Continue at own luck.";
+- else
+- echo "$kmajor.$kminor.$kmicro.$kstable in $kbuilddir";
+- if test "$kmajor" -gt 2 -o "$kminor" -gt 6 -o "$kmicro" -gt 38; then
+- echo "WARNING: You are trying a newer kernel. Results may vary. :-)";
+- elif test \( "$kmajor" -lt 2 -o \
+- \( "$kmajor" -eq 2 -a "$kminor" -lt 6 \) -o \
+- \( "$kmajor" -eq 2 -a "$kminor" -eq 0 -a "$kmicro" -lt 17 \) -o \
+- \( "$kmajor" -eq 2 -a "$kminor" -eq 6 -a "$kmicro" -eq 18 -a \
+- "$kstable" -lt 5 \) \); then
+- echo "ERROR: That kernel version is not supported. Please see INSTALL for minimum configuration.";
+- exit 1;
+- fi;