features: add experimental gpio-chardev-support flag

Due to limitations imposed by the kernel support, the gpio-chardev interface
is considered experimental and needs experimental.gpio-chardev-support
setting to be enabled in snapd, either explicitly at runtime or through
the defaults section in gadget.yaml.

Signed-off-by: Zeyad Gouda <[email protected]>

features/features.go

@@ -75,6 +75,8 @@ const (
 	ConfdbControl
 	// AppArmorPrompting enables AppArmor to prompt the user for permission when apps perform certain operations.
 	AppArmorPrompting
+	// GPIOChardevSupport enables experimental gpio-chardev interface.
+	GPIOChardevSupport
 
 	// lastFeature is the final known feature, it is only used for testing.
 	lastFeature
@@ -124,6 +126,8 @@ var featureNames = map[SnapdFeature]string{
 	ConfdbControl: "confdb-control",
 
 	AppArmorPrompting: "apparmor-prompting",
+
+	GPIOChardevSupport: "gpio-chardev-support",
 }
 
 // featuresEnabledWhenUnset contains a set of features that are enabled when not explicitly configured.

features/features_test.go

@@ -64,6 +64,7 @@ func (*featureSuite) TestName(c *C) {
 	check(features.Confdbs, "confdbs")
 	check(features.ConfdbControl, "confdb-control")
 	check(features.AppArmorPrompting, "apparmor-prompting")
+	check(features.GPIOChardevSupport, "gpio-chardev-support")
 
 	c.Check(tested, Equals, features.NumberOfFeatures())
 	c.Check(func() { _ = features.SnapdFeature(1000).String() }, PanicMatches, "unknown feature flag code 1000")
@@ -104,6 +105,7 @@ func (*featureSuite) TestIsExported(c *C) {
 	check(features.Confdbs, true)
 	check(features.ConfdbControl, false)
 	check(features.AppArmorPrompting, true)
+	check(features.GPIOChardevSupport, false)
 
 	c.Check(tested, Equals, features.NumberOfFeatures())
 }
@@ -229,6 +231,7 @@ func (*featureSuite) TestIsEnabledWhenUnset(c *C) {
 	check(features.Confdbs, false)
 	check(features.AppArmorPrompting, false)
 	check(features.ConfdbControl, false)
+	check(features.GPIOChardevSupport, false)
 
 	c.Check(tested, Equals, features.NumberOfFeatures())
 }