qemu: use 9p by default

.github/workflows/test.yml

@@ -256,6 +256,15 @@ jobs:
       if: matrix.template == '../hack/test-templates/test-misc.yaml'
     - name: "Show cache"
       run: ./hack/debug-cache.sh
+    - name: "Adjust LIMACTL_CREATE_ARGS"
+      # Change the mount type from 9p to reverse-sshfs, as a workaround for:
+      #
+      # > level=fatal msg="failed to get unprivileged mount flags for \"/home/runner/lima-container-engine-test-tmp/random\": stat /home/runner/lima-container-engine-test-tmp/random: no such file or directory"
+      #
+      # The issue is not reproducible on a local MacBook.
+      # https://github.com/lima-vm/lima/issues/2701
+      run: echo "LIMACTL_CREATE_ARGS=${LIMACTL_CREATE_ARGS} --mount-type=reverse-sshfs" >>$GITHUB_ENV
+      if: matrix.template == 'archlinux.yaml'
     - name: "Test"
       uses: nick-fields/retry@v3
       with:

examples/almalinux-8.yaml

@@ -16,6 +16,7 @@ images:
   arch: "x86_64"
 - location: "https://repo.almalinux.org/almalinux/8/cloud/aarch64/images/AlmaLinux-8-GenericCloud-latest.aarch64.qcow2"
   arch: "aarch64"
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

examples/almalinux-9.yaml

@@ -13,6 +13,7 @@ images:
   arch: "x86_64"
 - location: "https://repo.almalinux.org/almalinux/9/cloud/aarch64/images/AlmaLinux-9-GenericCloud-latest.aarch64.qcow2"
   arch: "aarch64"
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

examples/centos-stream-9.yaml

@@ -14,6 +14,7 @@ images:
   arch: "x86_64"
 - location: "https://cloud.centos.org/centos/9-stream/aarch64/images/CentOS-Stream-GenericCloud-9-latest.aarch64.qcow2"
   arch: "aarch64"
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

examples/debian-11.yaml

@@ -13,7 +13,7 @@ images:
   arch: "x86_64"
 - location: "https://cloud.debian.org/images/cloud/bullseye/latest/debian-11-genericcloud-arm64.qcow2"
   arch: "aarch64"
-
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

examples/debian-12.yaml

@@ -13,7 +13,7 @@ images:
   arch: "x86_64"
 - location: "https://cloud.debian.org/images/cloud/bookworm/latest/debian-12-genericcloud-arm64.qcow2"
   arch: "aarch64"
-
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

examples/default.yaml

@@ -71,8 +71,7 @@ mounts:
   # Configure the mountPoint inside the guest.
   # 🟢 Builtin default: value of location
   mountPoint: null
-  # CAUTION: `writable` SHOULD be false for the home directory.
-  # Setting `writable` to true is possible, but untested and dangerous.
+  # Setting `writable` to true is discouraged when mountType is set to "reverse-sshfs".
   # 🟢 Builtin default: false
   writable: null
   sshfs:
@@ -112,9 +111,14 @@ mounts:
   # 🔵 This file: true (only for "/tmp/lima")
   writable: true
 
-# Mount type for above mounts, such as "reverse-sshfs" (from sshocker), "9p" (EXPERIMENTAL, from QEMU’s virtio-9p-pci, aka virtfs),
+# List of mount types not supported by the kernel of this distro.
+# Also used to resolve the default mount type when not explicitly specified.
+# 🟢 Builtin default: null
+mountTypesUnsupported: null
+
+# Mount type for above mounts, such as "reverse-sshfs" (from sshocker), "9p" (EXPERIMENTAL until Lima v1.0, from QEMU’s virtio-9p-pci, aka virtfs),
 # or "virtiofs" (EXPERIMENTAL, needs `vmType: vz`; will graduate from experimental in Lima v1.0)
-# 🟢 Builtin default: "reverse-sshfs" (for QEMU), "virtiofs" (for vz)
+# 🟢 Builtin default: "default" (resolved to be "9p" for QEMU since Lima v1.0, "virtiofs" for vz)
 mountType: null
 
 # Enable inotify support for mounted directories (EXPERIMENTAL)

examples/experimental/9p.yaml

@@ -1,3 +1,11 @@
+# ⚠️ ⚠️ ⚠️ `template://experimental/9p` will be removed in Lima v1.0,
+# as 9p will graduate from experimental and will be the default mount type for QEMU.
+#
+# For Lima v1.0 and later, use the following command instead:
+# ```
+# limactl create --vm-type=qemu template://default
+# ```
+
 # This template requires Lima v0.10.0 or later.
 # On macOS hosts, QEMU needs to be v7.0.0 or later. Homebrew's QEMU v6.2.0_1 can be used too.
 # This template is planned to be merged to default.yaml in Lima v1.0 (ETA: 2022 Q2).

examples/experimental/opensuse-tumbleweed.yaml

@@ -5,6 +5,7 @@ images:
   arch: "x86_64"
 - location: "https://download.opensuse.org/ports/aarch64/tumbleweed/appliances/openSUSE-Tumbleweed-Minimal-VM.aarch64-Cloud.qcow2"
   arch: "aarch64"
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

examples/opensuse-leap.yaml

@@ -5,6 +5,7 @@ images:
   arch: "x86_64"
 - location: "https://download.opensuse.org/distribution/leap/15.6/appliances/openSUSE-Leap-15.6-Minimal-VM.aarch64-Cloud.qcow2"
   arch: "aarch64"
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

examples/oraclelinux-8.yaml

@@ -12,6 +12,7 @@ images:
 - location: "https://yum.oracle.com/templates/OracleLinux/OL8/u10/aarch64/OL8U10_aarch64-kvm-cloud-b100.qcow2"
   arch: "aarch64"
   digest: "sha256:def7b8055e275507a593f07dc6076a2adc5967af046c003072b479e69f25f407"
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

examples/oraclelinux-9.yaml

@@ -9,6 +9,7 @@ images:
 - location: "https://yum.oracle.com/templates/OracleLinux/OL9/u4/aarch64/OL9U4_aarch64-kvm-cloud-b90.qcow2"
   arch: "aarch64"
   digest: "sha256:1f4e20190e87c76e8c3b4a9e15e660972386cbfa4f128e5cdcd8faa43a713d44"
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

examples/rocky-8.yaml

@@ -16,6 +16,7 @@ images:
   arch: "x86_64"
 - location: "https://dl.rockylinux.org/pub/rocky/8/images/aarch64/Rocky-8-GenericCloud.latest.aarch64.qcow2"
   arch: "aarch64"
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

examples/rocky-9.yaml

@@ -14,6 +14,7 @@ images:
   arch: "x86_64"
 - location: "https://dl.rockylinux.org/pub/rocky/9/images/aarch64/Rocky-9-GenericCloud.latest.aarch64.qcow2"
   arch: "aarch64"
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
 - location: "/tmp/lima"

hack/test-templates/test-misc.yaml

@@ -1,5 +1,6 @@
 # The test template for testing misc configurations:
 # - disk
+# - snapshots
 # - (More to come)
 #
 # This template requires Lima v1.0.0-alpha.0 or later.
@@ -18,6 +19,8 @@ images:
 - location: "https://cloud-images.ubuntu.com/releases/24.04/release/ubuntu-24.04-server-cloudimg-arm64.img"
   arch: "aarch64"
 
+# 9p is not compatible with `limactl snapshot`
+mountTypesUnsupported: ["9p"]
 mounts:
 - location: "~"
   writable: true

pkg/limayaml/defaults.go

@@ -27,6 +27,7 @@ import (
 	"github.com/lima-vm/lima/pkg/ptr"
 	"github.com/lima-vm/lima/pkg/store/dirnames"
 	"github.com/lima-vm/lima/pkg/store/filenames"
+	"github.com/lima-vm/lima/pkg/version/versionutil"
 )
 
 const (
@@ -171,6 +172,17 @@ func defaultGuestInstallPrefix() string {
 //   - CACertificates Files and Certs are uniquely appended in d, y, o order
 func FillDefault(y, d, o *LimaYAML, filePath string) {
 	instDir := filepath.Dir(filePath)
+
+	// existingLimaVersion can be empty if the instance was created with Lima prior to v0.20,
+	// or, when editing a template file without an instance (`limactl edit foo.yaml`)
+	var existingLimaVersion string
+	limaVersionFile := filepath.Join(instDir, filenames.LimaVersion)
+	if b, err := os.ReadFile(limaVersionFile); err == nil {
+		existingLimaVersion = strings.TrimSpace(string(b))
+	} else if !errors.Is(err, os.ErrNotExist) {
+		logrus.WithError(err).Warnf("Failed to read %q", limaVersionFile)
+	}
+
 	if y.VMType == nil {
 		y.VMType = d.VMType
 	}
@@ -547,21 +559,41 @@ func FillDefault(y, d, o *LimaYAML, filePath string) {
 		}
 	}
 
+	y.MountTypesUnsupported = append(append(o.MountTypesUnsupported, y.MountTypesUnsupported...), d.MountTypesUnsupported...)
+	mountTypesUnsupported := make(map[string]struct{})
+	for _, f := range y.MountTypesUnsupported {
+		mountTypesUnsupported[f] = struct{}{}
+	}
 	// MountType has to be resolved before resolving Mounts
 	if y.MountType == nil {
 		y.MountType = d.MountType
 	}
 	if o.MountType != nil {
 		y.MountType = o.MountType
 	}
-	if y.MountType == nil || *y.MountType == "" {
-		if *y.VMType == VZ {
+	if y.MountType == nil || *y.MountType == "" || *y.MountType == "default" {
+		switch *y.VMType {
+		case VZ:
 			y.MountType = ptr.Of(VIRTIOFS)
-		} else {
+		case QEMU:
+			y.MountType = ptr.Of(NINEP)
+			if _, ok := mountTypesUnsupported[NINEP]; ok {
+				// Use REVSSHFS if the instance does not support 9p
+				y.MountType = ptr.Of(REVSSHFS)
+			} else if isExistingInstanceDir(instDir) && !versionutil.GreaterEqual(existingLimaVersion, "1.0.0") {
+				// Use REVSSHFS if the instance was created with Lima prior to v1.0
+				y.MountType = ptr.Of(REVSSHFS)
+			}
+		default:
 			y.MountType = ptr.Of(REVSSHFS)
 		}
 	}
 
+	if _, ok := mountTypesUnsupported[*y.MountType]; ok {
+		// We cannot return an error here, but Validate() will return it.
+		logrus.Warnf("Unsupported mount type: %q", *y.MountType)
+	}
+
 	if y.MountInotify == nil {
 		y.MountInotify = d.MountInotify
 	}

pkg/limayaml/limayaml.go

@@ -7,33 +7,34 @@ import (
 )
 
 type LimaYAML struct {
-	MinimumLimaVersion *string       `yaml:"minimumLimaVersion,omitempty" json:"minimumLimaVersion,omitempty"`
-	VMType             *VMType       `yaml:"vmType,omitempty" json:"vmType,omitempty"`
-	VMOpts             VMOpts        `yaml:"vmOpts,omitempty" json:"vmOpts,omitempty"`
-	OS                 *OS           `yaml:"os,omitempty" json:"os,omitempty"`
-	Arch               *Arch         `yaml:"arch,omitempty" json:"arch,omitempty"`
-	Images             []Image       `yaml:"images" json:"images"` // REQUIRED
-	CPUType            CPUType       `yaml:"cpuType,omitempty" json:"cpuType,omitempty"`
-	CPUs               *int          `yaml:"cpus,omitempty" json:"cpus,omitempty"`
-	Memory             *string       `yaml:"memory,omitempty" json:"memory,omitempty"` // go-units.RAMInBytes
-	Disk               *string       `yaml:"disk,omitempty" json:"disk,omitempty"`     // go-units.RAMInBytes
-	AdditionalDisks    []Disk        `yaml:"additionalDisks,omitempty" json:"additionalDisks,omitempty"`
-	Mounts             []Mount       `yaml:"mounts,omitempty" json:"mounts,omitempty"`
-	MountType          *MountType    `yaml:"mountType,omitempty" json:"mountType,omitempty"`
-	MountInotify       *bool         `yaml:"mountInotify,omitempty" json:"mountInotify,omitempty"`
-	SSH                SSH           `yaml:"ssh,omitempty" json:"ssh,omitempty"` // REQUIRED (FIXME)
-	Firmware           Firmware      `yaml:"firmware,omitempty" json:"firmware,omitempty"`
-	Audio              Audio         `yaml:"audio,omitempty" json:"audio,omitempty"`
-	Video              Video         `yaml:"video,omitempty" json:"video,omitempty"`
-	Provision          []Provision   `yaml:"provision,omitempty" json:"provision,omitempty"`
-	UpgradePackages    *bool         `yaml:"upgradePackages,omitempty" json:"upgradePackages,omitempty"`
-	Containerd         Containerd    `yaml:"containerd,omitempty" json:"containerd,omitempty"`
-	GuestInstallPrefix *string       `yaml:"guestInstallPrefix,omitempty" json:"guestInstallPrefix,omitempty"`
-	Probes             []Probe       `yaml:"probes,omitempty" json:"probes,omitempty"`
-	PortForwards       []PortForward `yaml:"portForwards,omitempty" json:"portForwards,omitempty"`
-	CopyToHost         []CopyToHost  `yaml:"copyToHost,omitempty" json:"copyToHost,omitempty"`
-	Message            string        `yaml:"message,omitempty" json:"message,omitempty"`
-	Networks           []Network     `yaml:"networks,omitempty" json:"networks,omitempty"`
+	MinimumLimaVersion    *string       `yaml:"minimumLimaVersion,omitempty" json:"minimumLimaVersion,omitempty"`
+	VMType                *VMType       `yaml:"vmType,omitempty" json:"vmType,omitempty"`
+	VMOpts                VMOpts        `yaml:"vmOpts,omitempty" json:"vmOpts,omitempty"`
+	OS                    *OS           `yaml:"os,omitempty" json:"os,omitempty"`
+	Arch                  *Arch         `yaml:"arch,omitempty" json:"arch,omitempty"`
+	Images                []Image       `yaml:"images" json:"images"` // REQUIRED
+	CPUType               CPUType       `yaml:"cpuType,omitempty" json:"cpuType,omitempty"`
+	CPUs                  *int          `yaml:"cpus,omitempty" json:"cpus,omitempty"`
+	Memory                *string       `yaml:"memory,omitempty" json:"memory,omitempty"` // go-units.RAMInBytes
+	Disk                  *string       `yaml:"disk,omitempty" json:"disk,omitempty"`     // go-units.RAMInBytes
+	AdditionalDisks       []Disk        `yaml:"additionalDisks,omitempty" json:"additionalDisks,omitempty"`
+	Mounts                []Mount       `yaml:"mounts,omitempty" json:"mounts,omitempty"`
+	MountTypesUnsupported []string      `yaml:"mountTypesUnsupported,omitempty" json:"mountTypesUnsupported,omitempty"`
+	MountType             *MountType    `yaml:"mountType,omitempty" json:"mountType,omitempty"`
+	MountInotify          *bool         `yaml:"mountInotify,omitempty" json:"mountInotify,omitempty"`
+	SSH                   SSH           `yaml:"ssh,omitempty" json:"ssh,omitempty"` // REQUIRED (FIXME)
+	Firmware              Firmware      `yaml:"firmware,omitempty" json:"firmware,omitempty"`
+	Audio                 Audio         `yaml:"audio,omitempty" json:"audio,omitempty"`
+	Video                 Video         `yaml:"video,omitempty" json:"video,omitempty"`
+	Provision             []Provision   `yaml:"provision,omitempty" json:"provision,omitempty"`
+	UpgradePackages       *bool         `yaml:"upgradePackages,omitempty" json:"upgradePackages,omitempty"`
+	Containerd            Containerd    `yaml:"containerd,omitempty" json:"containerd,omitempty"`
+	GuestInstallPrefix    *string       `yaml:"guestInstallPrefix,omitempty" json:"guestInstallPrefix,omitempty"`
+	Probes                []Probe       `yaml:"probes,omitempty" json:"probes,omitempty"`
+	PortForwards          []PortForward `yaml:"portForwards,omitempty" json:"portForwards,omitempty"`
+	CopyToHost            []CopyToHost  `yaml:"copyToHost,omitempty" json:"copyToHost,omitempty"`
+	Message               string        `yaml:"message,omitempty" json:"message,omitempty"`
+	Networks              []Network     `yaml:"networks,omitempty" json:"networks,omitempty"`
 	// `network` was deprecated in Lima v0.7.0, removed in Lima v0.14.0. Use `networks` instead.
 	Env          map[string]string `yaml:"env,omitempty" json:"env,omitempty"`
 	Param        map[string]string `yaml:"param,omitempty" json:"param,omitempty"`

pkg/limayaml/validate.go

@@ -185,6 +185,12 @@ func Validate(y *LimaYAML, warn bool) error {
 		return fmt.Errorf("field `mountType` must be %q or %q or %q, or %q, got %q", REVSSHFS, NINEP, VIRTIOFS, WSLMount, *y.MountType)
 	}
 
+	for _, f := range y.MountTypesUnsupported {
+		if f == *y.MountType {
+			return fmt.Errorf("field `mountType` must not be one of %v (`mountTypesUnsupported`), got %q", y.MountTypesUnsupported, *y.MountType)
+		}
+	}
+
 	if warn && runtime.GOOS != "linux" {
 		for i, mount := range y.Mounts {
 			if mount.Virtiofs.QueueSize != nil {
@@ -508,9 +514,6 @@ func validatePort(field string, port int) error {
 }
 
 func warnExperimental(y *LimaYAML) {
-	if *y.MountType == NINEP {
-		logrus.Warn("`mountType: 9p` is experimental")
-	}
 	if *y.MountType == VIRTIOFS && runtime.GOOS == "linux" {
 		logrus.Warn("`mountType: virtiofs` on Linux is experimental")
 	}

pkg/version/versionutil/versionutil.go

@@ -15,26 +15,34 @@ func Parse(version string) (*semver.Version, error) {
 	return semver.NewVersion(version)
 }
 
-// GreaterThan returns true if the Lima version used to create an instance is greater
-// than a specific older version. Always returns false if the Lima version is the empty string.
-// Unparsable lima versions (like SHA1 commit ids) are treated as the latest version and return true.
-// limaVersion is a `github describe` string, not a semantic version. So "0.19.1-16-gf3dc6ed.m"
-// will be considered greater than "0.19.1".
-func GreaterThan(limaVersion, oldVersion string) bool {
+func compare(limaVersion, oldVersion string) int {
 	if limaVersion == "" {
-		return false
+		if oldVersion == "" {
+			return 0
+		}
+		return -1
 	}
 	version, err := Parse(limaVersion)
 	if err != nil {
-		return true
+		return 1
 	}
-	switch version.Compare(*semver.New(oldVersion)) {
-	case -1:
-		return false
-	case +1:
-		return true
-	case 0:
-		return strings.Contains(limaVersion, "-")
+	cmp := version.Compare(*semver.New(oldVersion))
+	if cmp == 0 && strings.Contains(limaVersion, "-") {
+		cmp = 1
 	}
-	panic("unreachable")
+	return cmp
+}
+
+// GreaterThan returns true if the Lima version used to create an instance is greater
+// than a specific older version. Always returns false if the Lima version is the empty string.
+// Unparsable lima versions (like SHA1 commit ids) are treated as the latest version and return true.
+// limaVersion is a `github describe` string, not a semantic version. So "0.19.1-16-gf3dc6ed.m"
+// will be considered greater than "0.19.1".
+func GreaterThan(limaVersion, oldVersion string) bool {
+	return compare(limaVersion, oldVersion) > 0
+}
+
+// GreaterEqual return true if limaVersion >= oldVersion.
+func GreaterEqual(limaVersion, oldVersion string) bool {
+	return compare(limaVersion, oldVersion) >= 0
 }

pkg/version/versionutil/versionutil_test.go

@@ -14,3 +14,13 @@ func TestGreaterThan(t *testing.T) {
 	assert.Equal(t, GreaterThan("0.2.0", "0.1.0"), true)
 	assert.Equal(t, GreaterThan("abacab", "0.1.0"), true)
 }
+
+func TestGreaterEqual(t *testing.T) {
+	assert.Equal(t, GreaterEqual("", ""), true)
+	assert.Equal(t, GreaterEqual("", "0.1.0"), false)
+	assert.Equal(t, GreaterEqual("0.0.1", "0.1.0"), false)
+	assert.Equal(t, GreaterEqual("0.1.0", "0.1.0"), true)
+	assert.Equal(t, GreaterEqual("0.1.0-2", "0.1.0"), true)
+	assert.Equal(t, GreaterEqual("0.2.0", "0.1.0"), true)
+	assert.Equal(t, GreaterEqual("abacab", "0.1.0"), true)
+}

pkg/vz/vz_driver_darwin.go

@@ -39,6 +39,7 @@ var knownYamlProperties = []string{
 	"Message",
 	"Mounts",
 	"MountType",
+	"MountTypesUnsupported",
 	"MountInotify",
 	"Networks",
 	"OS",

website/content/en/docs/config/mount/_index.md

@@ -63,7 +63,7 @@ Lima prior to v0.10 had used "builtin" as the SFTP driver.
 
 ### 9p
 > **Warning**
-> "9p" mode is experimental
+> "9p" mode is experimental (will graduate from experimental in Lima v1.0)
 
 The "9p" mount type is implemented by using QEMU's virtio-9p-pci devices.
 virtio-9p-pci is also known as "virtfs", but note that this is unrelated to [virtio-fs](https://virtio-fs.gitlab.io/).