manifest: add support for selecting grub2.legacy

Older OS versions (RHEL 7) with older versions of grub2 don't support
BLS entries.  Setting NoBLS to true configures the bootloader with
traditional menu entries through the grub2.legacy osbuild stage.  This
requires specifying extra information for the OS to the pipeline:
version, product, and nick.

internal/distro/rhel7/images.go

@@ -182,6 +182,10 @@ func liveImage(workload workload.Workload,
 	img.Workload = workload
 	img.Compression = t.compression
 	img.PartTool = osbuild.PTSgdisk // all RHEL 7 images should use sgdisk
+	img.NoBLS = true                // RHEL 7 grub does not support BLS
+	img.OSProduct = t.arch.distro.product
+	img.OSVersion = t.arch.distro.osVersion
+	img.OSNick = t.arch.distro.nick
 
 	// TODO: move generation into LiveImage
 	pt, err := t.getPartitionTable(customizations.GetFilesystems(), options, rng)

internal/image/live.go

@@ -26,6 +26,11 @@ type LiveImage struct {
 	Filename         string
 	Compression      string
 	PartTool         osbuild.PartTool
+
+	NoBLS     bool
+	OSProduct string
+	OSVersion string
+	OSNick    string
 }
 
 func NewLiveImage() *LiveImage {
@@ -47,6 +52,10 @@ func (img *LiveImage) InstantiateManifest(m *manifest.Manifest,
 	osPipeline.OSCustomizations = img.OSCustomizations
 	osPipeline.Environment = img.Environment
 	osPipeline.Workload = img.Workload
+	osPipeline.NoBLS = img.NoBLS
+	osPipeline.OSProduct = img.OSProduct
+	osPipeline.OSVersion = img.OSVersion
+	osPipeline.OSNick = img.OSNick
 
 	imagePipeline := manifest.NewRawImage(m, buildPipeline, osPipeline)
 	imagePipeline.PartTool = img.PartTool

internal/manifest/os.go

@@ -130,6 +130,13 @@ type OS struct {
 	packageSpecs []rpmmd.PackageSpec
 	platform     platform.Platform
 	kernelVer    string
+
+	// NoBLS configures the image bootloader with traditional menu entries
+	// instead of BLS. Required for legacy systems like RHEL 7.
+	NoBLS     bool
+	OSProduct string
+	OSVersion string
+	OSNick    string
 }
 
 // NewOS creates a new OS pipeline. build is the build pipeline to use for
@@ -287,11 +294,13 @@ func (p *OS) serialize() osbuild.Pipeline {
 	}
 	pipeline.AddStage(osbuild.NewRPMStage(rpmOptions, osbuild.NewRpmStageSourceFilesInputs(p.packageSpecs)))
 
-	// If the /boot is on a separate partition, the prefix for the BLS stage must be ""
+	if !p.NoBLS {
-	if p.PartitionTable == nil || p.PartitionTable.FindMountable("/boot") == nil {
+		// If the /boot is on a separate partition, the prefix for the BLS stage must be ""
-		pipeline.AddStage(osbuild.NewFixBLSStage(&osbuild.FixBLSStageOptions{}))
+		if p.PartitionTable == nil || p.PartitionTable.FindMountable("/boot") == nil {
-	} else {
+			pipeline.AddStage(osbuild.NewFixBLSStage(&osbuild.FixBLSStageOptions{}))
-		pipeline.AddStage(osbuild.NewFixBLSStage(&osbuild.FixBLSStageOptions{Prefix: common.ToPtr("")}))
+		} else {
+			pipeline.AddStage(osbuild.NewFixBLSStage(&osbuild.FixBLSStageOptions{Prefix: common.ToPtr("")}))
+		}
 	}
 
 	if len(p.Containers) > 0 {
@@ -507,30 +516,52 @@ func (p *OS) serialize() osbuild.Pipeline {
 		case platform.ARCH_S390X:
 			bootloader = osbuild.NewZiplStage(new(osbuild.ZiplStageOptions))
 		default:
-			var options *osbuild.GRUB2StageOptions
+			if p.NoBLS {
-			options = osbuild.NewGrub2StageOptionsUnified(pt,
+				// BLS entries not supported: use grub2.legacy
-				p.kernelVer,
+				id := "76a22bf4-f153-4541-b6c7-0332c0dfaeac"
-				p.platform.GetUEFIVendor() != "",
+				product := osbuild.GRUB2Product{
-				p.platform.GetBIOSPlatform(),
+					Name:    p.OSProduct,
-				p.platform.GetUEFIVendor(), false)
+					Version: p.OSVersion,
-			if cfg := p.Grub2Config; cfg != nil {
+					Nick:    p.OSNick,
-				// TODO: don't store Grub2Config in OSPipeline, making the overrides unnecessary
-				// grub2.Config.Default is owned and set by `NewGrub2StageOptionsUnified`
-				// and thus we need to preserve it
-				if options.Config != nil {
-					cfg.Default = options.Config.Default
 				}
 
-				options.Config = cfg
+				rescueVer, _ := rpmmd.GetVerStrFromPackageSpecList(p.packageSpecs, "dracut-config-rescue")
-			}
+				hasRescue := rescueVer != ""
-			if p.KernelOptionsBootloader {
+				bootloader = osbuild.NewGrub2LegacyStage(
-				options.WriteCmdLine = nil
+					osbuild.NewGrub2LegacyStageOptions(
-				if options.UEFI != nil {
+						p.Grub2Config,
-					options.UEFI.Unified = false
+						p.PartitionTable,
+						kernelOptions,
+						p.platform.GetBIOSPlatform(),
+						p.platform.GetUEFIVendor(),
+						osbuild.MakeGrub2MenuEntries(id, p.kernelVer, product, hasRescue),
+					),
+				)
+			} else {
+				options := osbuild.NewGrub2StageOptionsUnified(pt,
+					p.kernelVer,
+					p.platform.GetUEFIVendor() != "",
+					p.platform.GetBIOSPlatform(),
+					p.platform.GetUEFIVendor(), false)
+				if cfg := p.Grub2Config; cfg != nil {
+					// TODO: don't store Grub2Config in OSPipeline, making the overrides unnecessary
+					// grub2.Config.Default is owned and set by `NewGrub2StageOptionsUnified`
+					// and thus we need to preserve it
+					if options.Config != nil {
+						cfg.Default = options.Config.Default
+					}
+
+					options.Config = cfg
 				}
-				options.KernelOptions = strings.Join(kernelOptions, " ")
+				if p.KernelOptionsBootloader {
+					options.WriteCmdLine = nil
+					if options.UEFI != nil {
+						options.UEFI.Unified = false
+					}
+					options.KernelOptions = strings.Join(kernelOptions, " ")
+				}
+				bootloader = osbuild.NewGRUB2Stage(options)
 			}
-			bootloader = osbuild.NewGRUB2Stage(options)
 		}
 
 		pipeline.AddStage(bootloader)