diff -r 0ff5b3570cd6 -r c6d2311442ad scripts/build/libc/glibc-eglibc.sh-common
--- a/scripts/build/libc/glibc-eglibc.sh-common	Sat Jan 22 22:37:25 2011 +0100
+++ b/scripts/build/libc/glibc-eglibc.sh-common	Sat Jan 22 22:35:02 2011 +0100
@@ -134,7 +134,7 @@
     # We don't need to be conditional on wether the user did set different
     # values, as they CT_LIBC_GLIBC_EXTRA_CONFIG is passed after extra_config
 
-    extra_config+=("--enable-kernel=$(echo ${CT_LIBC_GLIBC_MIN_KERNEL} |sed -r -e 's/^([^.]+\.[^.]+\.[^.]+)(|\.[^.]+)$/\1/;')")
+    extra_config+=("$(do_libc_min_kernel_config)")
 
     case "${CT_THREADS}" in
         nptl)           extra_config+=("--with-__thread" "--with-tls");;
@@ -252,3 +252,37 @@
     addons_list="${addons_list%%${sep}}"
     echo "${addons_list##${sep}}"
 }
+
+# Compute up the minimum supported Linux kernel version
+do_libc_min_kernel_config() {
+    local min_kernel_config
+
+    case "${CT_LIBC_GLIBC_EXTRA_CONFIG}" in
+        *--enable-kernel*) ;;
+        *)  if [ "${CT_LIBC_GLIBC_KERNEL_VERSION_AS_HEADERS}" = "y" ]; then
+                # We can't rely on the kernel version from the configuration,
+                # because it might not be available if the user uses pre-installed
+                # headers. On the other hand, both method will have the kernel
+                # version installed in "usr/include/linux/version.h" in the sys-root.
+                # Parse that instead of having two code-paths.
+                version_code_file="${CT_SYSROOT_DIR}/usr/include/linux/version.h"
+                if [ ! -f "${version_code_file}" -o ! -r "${version_code_file}" ]; then
+                    CT_Abort "Linux version is unavailable in installed headers files"
+                fi
+                version_code="$( grep -E LINUX_VERSION_CODE "${version_code_file}"  \
+                                 |cut -d ' ' -f 3                                   \
+                               )"
+                version=$(((version_code>>16)&0xFF))
+                patchlevel=$(((version_code>>8)&0xFF))
+                sublevel=$((version_code&0xFF))
+                min_kernel_config="${version}.${patchlevel}.${sublevel}"
+            elif [ "${CT_LIBC_GLIBC_KERNEL_VERSION_CHOSEN}" = "y" ]; then
+                # Trim the fourth part of the linux version, keeping only the first three numbers
+                min_kernel_config="$( echo "${CT_LIBC_GLIBC_MIN_KERNEL_VERSION}"                \
+                                      |sed -r -e 's/^([^.]+\.[^.]+\.[^.]+)(|\.[^.]+)$/\1/;')"   \
+                                    )"
+            fi
+            echo "--enable-kernel=${min_kernel_config}"
+            ;;
+    esac
+}