config_tools: add schema of checker schemas

This patch adds a (meta) XML schema of those XML schema files specifying
the validation rules (using xs:assert constructs). This provide integrators
with a mechanism to confirm the well-formedness of those rules, especially
the customized annotations for advanced error reporting.

Tracked-On: #6690
Signed-off-by: Junjie Mao <junjie.mao@intel.com>

misc/config_tools/schema/checks/check_the_checkers.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+# Copyright (C) 2022 Intel Corporation.
+# SPDX-License-Identifier: BSD-3-Clause
+
+checks_dir=$(dirname $0)
+for checker in ${checks_dir}/*.xsd; do
+    xmllint --noout --schema ${checks_dir}/schema_of_checks/main.xsd ${checker}
+done

misc/config_tools/schema/checks/schema_of_checks/custom_annot.xsd

@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2022 Intel Corporation. -->
+<!-- SPDX-License-Identifier: BSD-3-Clause -->
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
+	   targetNamespace="https://projectacrn.org">
+
+  <xs:attribute name="severity">
+    <xs:simpleType>
+      <xs:restriction base="xs:string">
+	<xs:enumeration value="error" />
+	<xs:enumeration value="warning" />
+      </xs:restriction>
+    </xs:simpleType>
+  </xs:attribute>
+
+  <xs:attribute name="report-on" type="xs:string" />
+
+</xs:schema>

misc/config_tools/schema/checks/schema_of_checks/main.xsd

@@ -0,0 +1,41 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2022 Intel Corporation. -->
+<!-- SPDX-License-Identifier: BSD-3-Clause -->
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
+	   xmlns:acrn="https://projectacrn.org"
+	   targetNamespace="http://www.w3.org/2001/XMLSchema">
+
+  <xs:import namespace="https://projectacrn.org" schemaLocation="custom_annot.xsd" />
+
+  <xs:element name="documentation" type="xs:string" />
+
+  <xs:element name="annotation">
+    <xs:complexType>
+      <xs:sequence>
+	<xs:element ref="xs:documentation" />
+      </xs:sequence>
+      <xs:attribute ref="acrn:severity" />
+      <xs:attribute ref="acrn:report-on" />
+    </xs:complexType>
+  </xs:element>
+
+  <xs:element name="assert">
+    <xs:complexType>
+      <xs:sequence>
+	<xs:element ref="xs:annotation" />
+      </xs:sequence>
+      <xs:attribute name="test" type="xs:string"/>
+    </xs:complexType>
+  </xs:element>
+
+  <xs:element name="schema">
+    <xs:complexType>
+      <xs:sequence>
+	<xs:element ref="xs:assert" maxOccurs="unbounded" />
+      </xs:sequence>
+
+      <xs:anyAttribute namespace="##other" processContents="lax"/>
+    </xs:complexType>
+  </xs:element>
+
+</xs:schema>