distro/rhel8: introduce s390x support

This patch introduces support for s390x architecture. It has some
specific requirements like using kernel-cmdline stage before the RPM
stage because RPM scriptlets require these values to be present in the
system already. It also uses zipl stage and bootloader as opposed to all
the other architectures.

internal/distro/rhel8/distro.go

@@ -228,12 +228,21 @@ func (t *imageType) pipeline(c *blueprint.Customizations, options distro.ImageOp
 	p := &osbuild.Pipeline{}
 	p.SetBuild(t.buildPipeline(repos, *t.arch, buildPackageSpecs), "org.osbuild.rhel82")
 
+	if t.arch.Name() == "s390x" {
+		p.AddStage(osbuild.NewKernelCmdlineStage(&osbuild.KernelCmdlineStageOptions{
+			RootFsUUID: "0bd700f8-090f-4556-b797-b340297ea1bd",
+			KernelOpts: "net.ifnames=0 crashkernel=auto",
+		}))
+	}
+
 	p.AddStage(osbuild.NewRPMStage(t.rpmStageOptions(*t.arch, repos, packageSpecs)))
 	p.AddStage(osbuild.NewFixBLSStage())
 
 	if t.bootable {
 		p.AddStage(osbuild.NewFSTabStage(t.fsTabStageOptions(t.arch.uefi)))
-		p.AddStage(osbuild.NewGRUB2Stage(t.grub2StageOptions(t.kernelOptions, c.GetKernel(), t.arch.uefi)))
+		if t.arch.Name() != "s390x" {
+			p.AddStage(osbuild.NewGRUB2Stage(t.grub2StageOptions(t.kernelOptions, c.GetKernel(), t.arch.uefi)))
+		}
 	} else if t.rpmOstree {
 		p.AddStage(osbuild.NewFSTabStage(t.fsOstreeTabStageOptions()))
 	}
@@ -286,6 +295,10 @@ func (t *imageType) pipeline(c *blueprint.Customizations, options distro.ImageOp
 		p.AddStage(osbuild.NewFirewallStage(t.firewallStageOptions(firewall)))
 	}
 
+	if t.arch.Name() == "s390x" {
+		p.AddStage(osbuild.NewZiplStage(&osbuild.ZiplStageOptions{}))
+	}
+
 	p.AddStage(osbuild.NewSELinuxStage(t.selinuxStageOptions()))
 
 	if t.rpmOstree {
@@ -550,6 +563,28 @@ func qemuAssembler(format string, filename string, uefi bool, imageOptions distr
 					},
 				},
 			}
+		} else if arch.Name() == "s390x" {
+			options = osbuild.QEMUAssemblerOptions{
+				Bootloader: &osbuild.QEMUBootloader{
+					Type: "zipl",
+				},
+				Format:   format,
+				Filename: filename,
+				Size:     imageOptions.Size,
+				PTUUID:   "0x14fc63d2",
+				PTType:   "dos",
+				Partitions: []osbuild.QEMUPartition{
+					{
+						Start:    2048,
+						Bootable: true,
+						Filesystem: &osbuild.QEMUFilesystem{
+							Type:       "xfs",
+							UUID:       "0bd700f8-090f-4556-b797-b340297ea1bd",
+							Mountpoint: "/",
+						},
+					},
+				},
+			}
 		} else {
 			options = osbuild.QEMUAssemblerOptions{
 				Format:   format,
@@ -1052,9 +1087,15 @@ func New() distro.Distro {
 	s390x := architecture{
 		distro: &r,
 		name:   "s390x",
+		bootloaderPackages: []string{
+			"dracut-config-generic",
+			"s390utils-base",
+		},
+		uefi: false,
 	}
 	s390x.setImageTypes(
 		tarImgType,
+		qcow2ImageType,
 	)
 
 	r.setArches(x8664, aarch64, ppc64le, s390x)

internal/osbuild/qemu_assembler.go

@@ -33,8 +33,8 @@ type QEMUFilesystem struct {
 }
 
 type QEMUBootloader struct {
-	Type     string `json:"type"`
-	Platform string `json:"platform"`
+	Type     string `json:"type,omitempty"`
+	Platform string `json:"platform,omitempty"`
 }
 
 func (QEMUAssemblerOptions) isAssemblerOptions() {}