diff --git a/tools/testing/ktest/ktest.pl b/tools/testing/ktest/ktest.pl
index c34f0dedad2d..52f558efdb0a 100755
--- a/tools/testing/ktest/ktest.pl
+++ b/tools/testing/ktest/ktest.pl
@@ -2784,12 +2784,17 @@ my %dependency;
 sub assign_configs {
     my ($hash, $config) = @_;
 
+    doprint "Reading configs from $config\n";
+
     open (IN, $config)
 	or dodie "Failed to read $config";
 
     while (<IN>) {
+	chomp;
 	if (/^((CONFIG\S*)=.*)/) {
 	    ${$hash}{$2} = $1;
+	} elsif (/^(# (CONFIG\S*) is not set)/) {
+	    ${$hash}{$2} = $1;
 	}
     }
 
@@ -2841,54 +2846,98 @@ sub get_dependencies {
     return @deps;
 }
 
-sub create_config {
-    my @configs = @_;
+sub save_config {
+    my ($pc, $file) = @_;
 
-    open(OUT, ">$output_config") or dodie "Can not write to $output_config";
+    my %configs = %{$pc};
 
-    foreach my $config (@configs) {
-	print OUT "$config_set{$config}\n";
-	my @deps = get_dependencies $config;
-	foreach my $dep (@deps) {
-	    print OUT "$config_set{$dep}\n";
-	}
-    }
+    doprint "Saving configs into $file\n";
 
-    # turn off configs to keep off
-    foreach my $config (keys %config_off) {
-	print OUT "# $config is not set\n";
-    }
+    open(OUT, ">$file") or dodie "Can not write to $file";
 
-    # turn off configs that should be off for now
-    foreach my $config (@config_off_tmp) {
-	print OUT "# $config is not set\n";
-    }
-
-    foreach my $config (keys %config_ignore) {
-	print OUT "$config_ignore{$config}\n";
+    foreach my $config (keys %configs) {
+	print OUT "$configs{$config}\n";
     }
     close(OUT);
+}
+
+sub create_config {
+    my ($name, $pc) = @_;
+
+    doprint "Creating old config from $name configs\n";
+
+    save_config $pc, $output_config;
 
     make_oldconfig;
 }
 
+# compare two config hashes, and return configs with different vals.
+# It returns B's config values, but you can use A to see what A was.
+sub diff_config_vals {
+    my ($pa, $pb) = @_;
+
+    # crappy Perl way to pass in hashes.
+    my %a = %{$pa};
+    my %b = %{$pb};
+
+    my %ret;
+
+    foreach my $item (keys %a) {
+	if (defined($b{$item}) && $b{$item} ne $a{$item}) {
+	    $ret{$item} = $b{$item};
+	}
+    }
+
+    return %ret;
+}
+
+# compare two config hashes and return the configs in B but not A
+sub diff_configs {
+    my ($pa, $pb) = @_;
+
+    my %ret;
+
+    # crappy Perl way to pass in hashes.
+    my %a = %{$pa};
+    my %b = %{$pb};
+
+    foreach my $item (keys %b) {
+	if (!defined($a{$item})) {
+	    $ret{$item} = $b{$item};
+	}
+    }
+
+    return %ret;
+}
+
+# return if two configs are equal or not
+# 0 is equal +1 b has something a does not
+# +1 if a and b have a different item.
+# -1 if a has something b does not
 sub compare_configs {
-    my (%a, %b) = @_;
+    my ($pa, $pb) = @_;
+
+    my %ret;
+
+    # crappy Perl way to pass in hashes.
+    my %a = %{$pa};
+    my %b = %{$pb};
+
+    foreach my $item (keys %b) {
+	if (!defined($a{$item})) {
+	    return 1;
+	}
+	if ($a{$item} ne $b{$item}) {
+	    return 1;
+	}
+    }
 
     foreach my $item (keys %a) {
 	if (!defined($b{$item})) {
-	    print "diff $item\n";
-	    return 1;
+	    return -1;
 	}
-	delete $b{$item};
     }
 
-    my @keys = keys %b;
-    if ($#keys) {
-	print "diff2 $keys[0]\n";
-    }
-    return -1 if ($#keys >= 0);
-
     return 0;
 }
 
@@ -2923,253 +2972,204 @@ sub process_failed {
     doprint "***************************************\n\n";
 }
 
-sub run_config_bisect {
+# used for config bisecting
+my $good_config;
+my $bad_config;
 
-    my @start_list = keys %config_list;
+sub process_new_config {
+    my ($tc, $nc, $gc, $bc) = @_;
 
-    if ($#start_list < 0) {
-	doprint "No more configs to test!!!\n";
-	return -1;
+    my %tmp_config = %{$tc};
+    my %good_configs = %{$gc};
+    my %bad_configs = %{$bc};
+
+    my %new_configs;
+
+    my $runtest = 1;
+    my $ret;
+
+    create_config "tmp_configs", \%tmp_config;
+    assign_configs \%new_configs, $output_config;
+
+    $ret = compare_configs \%new_configs, \%bad_configs;
+    if (!$ret) {
+	doprint "New config equals bad config, try next test\n";
+	$runtest = 0;
     }
 
-    doprint "***** RUN TEST ***\n";
+    if ($runtest) {
+	$ret = compare_configs \%new_configs, \%good_configs;
+	if (!$ret) {
+	    doprint "New config equals good config, try next test\n";
+	    $runtest = 0;
+	}
+    }
+
+    %{$nc} = %new_configs;
+
+    return $runtest;
+}
+
+sub run_config_bisect {
+    my ($pgood, $pbad) = @_;
+
     my $type = $config_bisect_type;
+
+    my %good_configs = %{$pgood};
+    my %bad_configs = %{$pbad};
+
+    my %diff_configs = diff_config_vals \%good_configs, \%bad_configs;
+    my %b_configs = diff_configs \%good_configs, \%bad_configs;
+    my %g_configs = diff_configs \%bad_configs, \%good_configs;
+
+    my @diff_arr = keys %diff_configs;
+    my $len_diff = $#diff_arr + 1;
+
+    my @b_arr = keys %b_configs;
+    my $len_b = $#b_arr + 1;
+
+    my @g_arr = keys %g_configs;
+    my $len_g = $#g_arr + 1;
+
+    my $runtest = 1;
+    my %new_configs;
     my $ret;
-    my %current_config;
 
-    my $count = $#start_list + 1;
-    doprint "  $count configs to test\n";
+    # First, lets get it down to a single subset.
+    # Is the problem with a difference in values?
+    # Is the problem with a missing config?
+    # Is the problem with a config that breaks things?
 
-    my $half = int($#start_list / 2);
+    # Enable all of one set and see if we get a new bad
+    # or good config.
 
-    do {
-	my @tophalf = @start_list[0 .. $half];
+    # first set the good config to the bad values.
 
-	# keep the bottom half off
-	if ($half < $#start_list) {
-	    @config_off_tmp = @start_list[$half + 1 .. $#start_list];
-	} else {
-	    @config_off_tmp = ();
-	}
+    doprint "d=$len_diff g=$len_g b=$len_b\n";
 
-	create_config @tophalf;
-	read_current_config \%current_config;
+    # first lets enable things in bad config that are enabled in good config
 
-	$count = $#tophalf + 1;
-	doprint "Testing $count configs\n";
-	my $found = 0;
-	# make sure we test something
-	foreach my $config (@tophalf) {
-	    if (defined($current_config{$config})) {
-		logit " $config\n";
-		$found = 1;
+    if ($len_diff > 0) {
+	if ($len_b > 0 || $len_g > 0) {
+	    my %tmp_config = %bad_configs;
+
+	    doprint "Set tmp config to be bad config with good config values\n";
+	    foreach my $item (@diff_arr) {
+		$tmp_config{$item} = $good_configs{$item};
 	    }
+
+	    $runtest = process_new_config \%tmp_config, \%new_configs,
+			    \%good_configs, \%bad_configs;
 	}
-	if (!$found) {
-	    # try the other half
-	    doprint "Top half produced no set configs, trying bottom half\n";
+    }
 
-	    # keep the top half off
-	    @config_off_tmp = @tophalf;
-	    @tophalf = @start_list[$half + 1 .. $#start_list];
+    if (!$runtest && $len_diff > 0) {
 
-	    create_config @tophalf;
-	    read_current_config \%current_config;
-	    foreach my $config (@tophalf) {
-		if (defined($current_config{$config})) {
-		    logit " $config\n";
-		    $found = 1;
-		}
-	    }
-	    if (!$found) {
-		doprint "Failed: Can't make new config with current configs\n";
-		foreach my $config (@start_list) {
-		    doprint "  CONFIG: $config\n";
-		}
-		return -1;
-	    }
-	    $count = $#tophalf + 1;
-	    doprint "Testing $count configs\n";
-	}
-
-	$ret = run_config_bisect_test $type;
-	if ($bisect_manual) {
-	    $ret = answer_bisect;
-	}
-	if ($ret) {
-	    process_passed %current_config;
-	    return 0;
-	}
-
-	doprint "This config had a failure.\n";
-	doprint "Removing these configs that were not set in this config:\n";
-	doprint "config copied to $outputdir/config_bad\n";
-	run_command "cp -f $output_config $outputdir/config_bad";
-
-	# A config exists in this group that was bad.
-	foreach my $config (keys %config_list) {
-	    if (!defined($current_config{$config})) {
-		doprint " removing $config\n";
-		delete $config_list{$config};
-	    }
-	}
-
-	@start_list = @tophalf;
-
-	if ($#start_list == 0) {
-	    process_failed $start_list[0];
+	if ($len_diff == 1) {
+	    doprint "The bad config setting is: $diff_arr[0]\n";
 	    return 1;
 	}
+	my %tmp_config = %bad_configs;
 
-	# remove half the configs we are looking at and see if
-	# they are good.
-	$half = int($#start_list / 2);
-    } while ($#start_list > 0);
+	my $half = int($#diff_arr / 2);
+	my @tophalf = @diff_arr[0 .. $half];
 
-    # we found a single config, try it again unless we are running manually
+	doprint "Settings bisect with top half:\n";
+	doprint "Set tmp config to be bad config with some good config values\n";
+	foreach my $item (@tophalf) {
+	    $tmp_config{$item} = $good_configs{$item};
+	}
 
-    if ($bisect_manual) {
-	process_failed $start_list[0];
-	return 1;
+	$runtest = process_new_config \%tmp_config, \%new_configs,
+			    \%good_configs, \%bad_configs;
+
+	if (!$runtest) {
+	    my %tmp_config = %bad_configs;
+
+	    doprint "Try bottom half\n";
+
+	    my @bottomhalf = @diff_arr[$half+1 .. $#diff_arr];
+
+	    foreach my $item (@bottomhalf) {
+		$tmp_config{$item} = $good_configs{$item};
+	    }
+
+	    $runtest = process_new_config \%tmp_config, \%new_configs,
+			    \%good_configs, \%bad_configs;
+	}
     }
 
-    my @tophalf = @start_list[0 .. 0];
-
-    $ret = run_config_bisect_test $type;
-    if ($ret) {
-	process_passed %current_config;
+    if ($runtest) {
+	$ret = run_config_bisect_test $type;
+	if ($ret) {
+	    doprint "NEW GOOD CONFIG\n";
+	    %good_configs = %new_configs;
+	    run_command "mv $good_config ${good_config}.last";
+	    save_config \%good_configs, $good_config;
+	    %{$pgood} = %good_configs;
+	} else {
+	    doprint "NEW BAD CONFIG\n";
+	    %bad_configs = %new_configs;
+	    run_command "mv $bad_config ${bad_config}.last";
+	    save_config \%bad_configs, $bad_config;
+	    %{$pbad} = %bad_configs;
+	}
 	return 0;
     }
 
-    process_failed $start_list[0];
-    return 1;
+    fail "Hmm, need to do a mix match?\n";
+    return -1;
 }
 
 sub config_bisect {
     my ($i) = @_;
 
-    my $start_config = $config_bisect;
+    my $type = $config_bisect_type;
 
-    my $tmpconfig = "$tmpdir/use_config";
+    $bad_config = $config_bisect;
 
     if (defined($config_bisect_good)) {
-	process_config_ignore $config_bisect_good;
-    }
-
-    # Make the file with the bad config and the min config
-    if (defined($minconfig)) {
-	# read the min config for things to ignore
-	run_command "cp $minconfig $tmpconfig" or
-	    dodie "failed to copy $minconfig to $tmpconfig";
+	$good_config = $config_bisect_good;
+    } elsif (defined($minconfig)) {
+	$good_config = $minconfig;
     } else {
-	unlink $tmpconfig;
-    }
-
-    if (-f $tmpconfig) {
-	load_force_config($tmpconfig);
-	process_config_ignore $tmpconfig;
-    }
-
-    # now process the start config
-    run_command "cp $start_config $output_config" or
-	dodie "failed to copy $start_config to $output_config";
-
-    # read directly what we want to check
-    my %config_check;
-    open (IN, $output_config)
-	or dodie "failed to open $output_config";
-
-    while (<IN>) {
-	if (/^((CONFIG\S*)=.*)/) {
-	    $config_check{$2} = $1;
-	}
-    }
-    close(IN);
-
-    # Now run oldconfig with the minconfig
-    make_oldconfig;
-
-    # check to see what we lost (or gained)
-    open (IN, $output_config)
-	or dodie "Failed to read $start_config";
-
-    my %removed_configs;
-    my %added_configs;
-
-    while (<IN>) {
-	if (/^((CONFIG\S*)=.*)/) {
-	    # save off all options
-	    $config_set{$2} = $1;
-	    if (defined($config_check{$2})) {
-		if (defined($config_ignore{$2})) {
-		    $removed_configs{$2} = $1;
-		} else {
-		    $config_list{$2} = $1;
-		}
-	    } elsif (!defined($config_ignore{$2})) {
-		$added_configs{$2} = $1;
-		$config_list{$2} = $1;
-	    }
-	} elsif (/^# ((CONFIG\S*).*)/) {
-	    # Keep these configs disabled
-	    $config_set{$2} = $1;
-	    $config_off{$2} = $1;
-	}
-    }
-    close(IN);
-
-    my @confs = keys %removed_configs;
-    if ($#confs >= 0) {
-	doprint "Configs overridden by default configs and removed from check:\n";
-	foreach my $config (@confs) {
-	    doprint " $config\n";
-	}
-    }
-    @confs = keys %added_configs;
-    if ($#confs >= 0) {
-	doprint "Configs appearing in make oldconfig and added:\n";
-	foreach my $config (@confs) {
-	    doprint " $config\n";
+	doprint "No config specified, checking if defconfig works";
+	my $ret = run_bisect_test $type, "defconfig";
+	if (!$ret) {
+	    fail "Have no good config to compare with, please set CONFIG_BISECT_GOOD";
+	    return 1;
 	}
+	$good_config = $output_config;
     }
 
-    my %config_test;
-    my $once = 0;
+    # we don't want min configs to cause issues here.
+    doprint "Disabling 'MIN_CONFIG' for this test\n";
+    undef $minconfig;
 
-    @config_off_tmp = ();
+    my %good_configs;
+    my %bad_configs;
+    my %tmp_configs;
+
+    doprint "Run good configs through make oldconfig\n";
+    assign_configs \%tmp_configs, $good_config;
+    create_config "$good_config", \%tmp_configs;
+    assign_configs \%good_configs, $output_config;
+
+    doprint "Run bad configs through make oldconfig\n";
+    assign_configs \%tmp_configs, $bad_config;
+    create_config "$bad_config", \%tmp_configs;
+    assign_configs \%bad_configs, $output_config;
+
+    $good_config = "$tmpdir/good_config";
+    $bad_config = "$tmpdir/bad_config";
+
+    save_config \%good_configs, $good_config;
+    save_config \%bad_configs, $bad_config;
 
-    # Sometimes kconfig does weird things. We must make sure
-    # that the config we autocreate has everything we need
-    # to test, otherwise we may miss testing configs, or
-    # may not be able to create a new config.
-    # Here we create a config with everything set.
-    create_config (keys %config_list);
-    read_current_config \%config_test;
-    foreach my $config (keys %config_list) {
-	if (!defined($config_test{$config})) {
-	    if (!$once) {
-		$once = 1;
-		doprint "Configs not produced by kconfig (will not be checked):\n";
-	    }
-	    doprint "  $config\n";
-	    delete $config_list{$config};
-	}
-    }
     my $ret;
 
-    if (defined($config_bisect_check) && $config_bisect_check) {
-	doprint " Checking to make sure bad config with min config fails\n";
-	create_config keys %config_list;
-	$ret = run_config_bisect_test $config_bisect_type;
-	if ($ret) {
-	    doprint " FAILED! Bad config with min config boots fine\n";
-	    return -1;
-	}
-	doprint " Bad config with min config fails as expected\n";
-    }
-
     do {
-	$ret = run_config_bisect;
+	$ret = run_config_bisect \%good_configs, \%bad_configs;
     } while (!$ret);
 
     return $ret if ($ret < 0);