newt: Generate link tables header

Adding pkg.link_tables field with link tables names will result
in generation of link_tables.ld.h file which will be used
in auto-generated linker script.

newt/builder/extcmd.go

@@ -184,6 +184,47 @@ func (t *TargetBuilder) execExtCmds(sf stage.StageFunc, userSrcDir string,
 	return nil
 }
 
+func getLinkTableEntry(name string) string {
+	indent := "        "
+
+	entry := indent + "__" + name + "_start__ = .;\n" +
+		indent + "KEEP(*(." + name + "))\n" +
+		indent + "__" + name + "_end__ = .;\n\n"
+
+	return entry
+}
+
+func (t *TargetBuilder) generateLinkTables() {
+	var s []string
+
+	for _, pkg := range t.res.LpkgRpkgMap {
+		s = append(s, pkg.Lpkg.LinkTables()...)
+	}
+
+	if len(s) == 0 {
+		return
+	}
+
+	dir := GeneratedBaseDir(t.target.FullName()) + "/link/include"
+	err := os.MkdirAll(dir, os.ModePerm)
+	if err != nil {
+		log.Error("Generate link tables error:\n", err)
+		return
+	}
+
+	linkHeader, err := os.Create(dir + "/link_tables.ld.h")
+	if err != nil {
+		log.Error("Generate link tables error:\n", err)
+		return
+	}
+
+	for _, linkTable := range s {
+		linkHeader.WriteString(getLinkTableEntry(linkTable))
+	}
+
+}
+
+//link tables
 // execPreBuildCmds runs the target's set of pre-build user commands.  It is an
 // error if any command fails (exits with a nonzero status).
 func (t *TargetBuilder) execPreBuildCmds(workDir string) error {

newt/builder/targetbuild.go

@@ -581,6 +581,8 @@ func (t *TargetBuilder) Build() error {
 		os.RemoveAll(workDir)
 	}()
 
+	t.generateLinkTables()
+
 	// Execute the set of pre-build user scripts.
 	if err := t.execPreBuildCmds(workDir); err != nil {
 		return err

newt/pkg/localpackage.go

@@ -59,6 +59,8 @@ type LocalPackage struct {
 	// General information about the package
 	desc *PackageDesc
 
+	linkTables []string
+
 	// Extra package-specific settings that don't come from syscfg.  For
 	// example, SELFTEST gets set when the newt test command is used.
 	injectedSettings *cfgv.Settings
@@ -145,6 +147,10 @@ func (pkg *LocalPackage) Desc() *PackageDesc {
 	return pkg.desc
 }
 
+func (pkg *LocalPackage) LinkTables() []string {
+	return pkg.linkTables
+}
+
 func (pkg *LocalPackage) SetName(name string) {
 	pkg.name = name
 }
@@ -197,6 +203,15 @@ func (pkg *LocalPackage) readDesc(yc ycfg.YCfg) (*PackageDesc, error) {
 	return pdesc, nil
 }
 
+func (pkg *LocalPackage) readLinkTables(yc ycfg.YCfg) ([]string, error) {
+	var err error
+
+	sections, err := yc.GetValStringSlice("pkg.link_tables", nil)
+	util.OneTimeWarningError(err)
+
+	return sections, nil
+}
+
 func (pkg *LocalPackage) sequenceString(key string) string {
 	var buffer bytes.Buffer
 
@@ -361,6 +376,8 @@ func (pkg *LocalPackage) Load() error {
 		return err
 	}
 
+	pkg.linkTables, err = pkg.readLinkTables(pkg.PkgY)
+
 	// Load syscfg settings.
 	pkg.SyscfgY, err = config.ReadFile(pkg.SyscfgYamlPath())
 	if err != nil && !util.IsNotExist(err) {