When run in an initrd and no root= argument is set (or is set to
root=gpt-auto) we will automatically look for the root partition on the
same disk the EFI ESP is located on.
Since we look for swap, /home and /srv on the disk the root partition is
located on, we hence have a fully discoverable chain:
Firmware discovers the EFI ESP partition → the initrd discovers the
root partition → the host OS discovers swap, /home, and /srv.
Note that this requires an EFI boot loader that sets the
LoaderDevicePartUUID EFI variable, such as Gummiboot.
<refnamediv>
<refname>systemd-gpt-auto-generator</refname>
<refpurpose>Generator for automatically discovering
<refnamediv>
<refname>systemd-gpt-auto-generator</refname>
<refpurpose>Generator for automatically discovering
- and mounting <filename>/home</filename> and <filename>/srv</filename>, as well as
+ and mounting root, <filename>/home</filename> and
+ <filename>/srv</filename> partitions, as well as
discovering and enabling swap partitions, based on GPT
partition type GUIDs.</refpurpose>
</refnamediv>
discovering and enabling swap partitions, based on GPT
partition type GUIDs.</refpurpose>
</refnamediv>
<title>Description</title>
<para><filename>systemd-gpt-auto-generator</filename>
<title>Description</title>
<para><filename>systemd-gpt-auto-generator</filename>
- is a unit generator that automatically discovers
+ is a unit generator that automatically discovers root,
<filename>/home</filename>, <filename>/srv</filename>
and swap partitions and creates mount and swap units
for them, based on the the partition type GUIDs of
<filename>/home</filename>, <filename>/srv</filename>
and swap partitions and creates mount and swap units
for them, based on the the partition type GUIDs of
<citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>),
or where the mount points are non-empty.</para>
<citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>),
or where the mount points are non-empty.</para>
- <para>This generator will only look for partitions on
- the same physical disk the root file system is stored
- on. This generator has no effect on systems where the
- root file system is distributed on multiple disks, for
- example via btrfs RAID.</para>
+ <para>This generator will only look for root
+ partitions on the same physical disk the EFI System
+ Partition (ESP) is located on. It will only look for
+ the other partitions on the same physical disk the
+ root file system is located on. These partitions will
+ not be search on systems where the root file system is
+ distributed on multiple disks, for example via btrfs
+ RAID.</para>
<para><filename>systemd-gpt-auto-generator</filename>
is useful for centralizing file system configuration
<para><filename>systemd-gpt-auto-generator</filename>
is useful for centralizing file system configuration
<title>Partition Type GUIDs</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>
<colspec colname="guid" />
<title>Partition Type GUIDs</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>
<colspec colname="guid" />
- <colspec colname="location" />
+ <colspec colname="name" />
<colspec colname="explanation" />
<thead>
<row>
<entry>Partition Type GUID</entry>
<colspec colname="explanation" />
<thead>
<row>
<entry>Partition Type GUID</entry>
- <entry>Location</entry>
<entry>Explanation</entry>
</row>
</thead>
<tbody>
<row>
<entry>Explanation</entry>
</row>
</thead>
<tbody>
<row>
- <entry>0657fd6d-a4ab-43c4-84e50933c84b4f4f</entry>
- <entry>Swap</entry>
- <entry>All swap partitions are enabled.</entry>
+ <entry>44479540-f297-41b2-9af7d131d5f0458a</entry>
+ <entry><filename>Root Partition (x86)</filename></entry>
+ <entry>On 32bit x86 systems the first x86 root partition on the disk the EFI ESP is located on is mounted to the root directory <filename>/</filename>.</entry>
+ </row>
+ <row>
+ <entry>4f68bce3-e8cd-4db1-96e7fbcaf984b709</entry>
+ <entry><filename>Root Partition (x86-64)</filename></entry>
+ <entry>On 64bit x86 systems the first x86-64 root partition on the disk the EFI ESP is located on is mounted to the root directory <filename>/</filename>.</entry>
</row>
<row>
<entry>933ac7e1-2eb4-4f13-b8440e14e2aef915</entry>
</row>
<row>
<entry>933ac7e1-2eb4-4f13-b8440e14e2aef915</entry>
- <entry><filename>/home</filename></entry>
- <entry>The first home partition on the disk is mounted to <filename>/home</filename>.</entry>
+ <entry>Home Partition</entry>
+ <entry>The first home partition on the disk the root partition is located on is mounted to <filename>/home</filename>.</entry>
</row>
<row>
<entry>3b8f8425-20e0-4f3b-907f1a25a76f98e8</entry>
</row>
<row>
<entry>3b8f8425-20e0-4f3b-907f1a25a76f98e8</entry>
- <entry><filename>/srv</filename></entry>
- <entry>The first server data partition on the disk is mounted to <filename>/srv</filename>.</entry>
+ <entry>Server Data Partition</entry>
+ <entry>The first server data partition on the disk the root partition is located on is mounted to <filename>/srv</filename>.</entry>
+ </row>
+ <row>
+ <entry>0657fd6d-a4ab-43c4-84e50933c84b4f4f</entry>
+ <entry>Swap</entry>
+ <entry>All swap partitions located on the disk the root partition is located on are enabled.</entry>
</row>
</tbody>
</tgroup>
</row>
</tbody>
</tgroup>
<para>Also note that
<citerefentry><refentrytitle>systemd-efi-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
<para>Also note that
<citerefentry><refentrytitle>systemd-efi-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- will mount the EFI System Partition to
- <filename>/boot</filename> is not otherwise mounted.</para>
+ will mount the EFI System Partition (ESP) to
+ <filename>/boot</filename> if not otherwise mounted.</para>
+
+ <para>When using this generator in conjunction with
+ btrfs file systems make sure to set the correct
+ default subvolumes on them, using <command>btrfs
+ subvolume set-default</command>.</para>
<para><filename>systemd-gpt-auto-generator</filename>
implements the <ulink
<para><filename>systemd-gpt-auto-generator</filename>
implements the <ulink
<citerefentry><refentrytitle>systemd-efi-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-efi-boot-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>btrfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
log_warning("Environment variable name '%s' is not valid. Ignoring.", value);
} else if (!streq(key, "systemd.restore_state") &&
log_warning("Environment variable name '%s' is not valid. Ignoring.", value);
} else if (!streq(key, "systemd.restore_state") &&
+ !streq(key, "systemd.gpt_auto") &&
(startswith(key, "systemd.") || startswith(key, "rd.systemd."))) {
const char *c;
(startswith(key, "systemd.") || startswith(key, "rd.systemd."))) {
const char *c;
#include "generator.h"
#include "gpt.h"
#include "fileio.h"
#include "generator.h"
#include "gpt.h"
#include "fileio.h"
static const char *arg_dest = "/tmp";
static const char *arg_dest = "/tmp";
+static bool arg_enabled = true;
+static bool arg_root_enabled = true;
+static bool arg_root_rw = false;
DEFINE_TRIVIAL_CLEANUP_FUNC(blkid_probe, blkid_free_probe);
#define _cleanup_blkid_freep_probe_ _cleanup_(blkid_free_probep)
DEFINE_TRIVIAL_CLEANUP_FUNC(blkid_probe, blkid_free_probe);
#define _cleanup_blkid_freep_probe_ _cleanup_(blkid_free_probep)
-static int add_mount(const char *id, const char *what, const char *where, const char *fstype, const char *description) {
+static int add_mount(
+ const char *id,
+ const char *what,
+ const char *where,
+ const char *fstype,
+ const char *options,
+ const char *description,
+ const char *post) {
+
_cleanup_free_ char *unit = NULL, *lnk = NULL, *crypto_what = NULL, *p = NULL;
_cleanup_fclose_ FILE *f = NULL;
int r;
_cleanup_free_ char *unit = NULL, *lnk = NULL, *crypto_what = NULL, *p = NULL;
_cleanup_fclose_ FILE *f = NULL;
int r;
assert(id);
assert(what);
assert(where);
assert(id);
assert(what);
assert(where);
assert(description);
if (path_is_mount_point(where, true) <= 0 &&
assert(description);
if (path_is_mount_point(where, true) <= 0 &&
- log_debug("Adding %s: %s %s", where, what, fstype);
+ log_debug("Adding %s: %s %s", where, what, strna(fstype));
- if (streq(fstype, "crypto_LUKS")) {
+ if (streq_ptr(fstype, "crypto_LUKS")) {
r = add_cryptsetup(id, what, &crypto_what);
if (r < 0)
r = add_cryptsetup(id, what, &crypto_what);
if (r < 0)
"Documentation=man:systemd-gpt-auto-generator(8)\n",
description);
"Documentation=man:systemd-gpt-auto-generator(8)\n",
description);
+ if (post)
+ fprintf(f, "Before=%s\n", post);
+
r = generator_write_fsck_deps(f, arg_dest, what, where, fstype);
if (r < 0)
return r;
r = generator_write_fsck_deps(f, arg_dest, what, where, fstype);
if (r < 0)
return r;
"Where=%s\n",
what, where);
"Where=%s\n",
what, where);
- if (fstype) {
- fprintf(f,
- "Type=%s\n",
- fstype);
- }
+ if (fstype)
+ fprintf(f, "Type=%s\n", fstype);
+
+ if (options)
+ fprintf(f, "Options=%s\n", options);
fflush(f);
if (ferror(f)) {
fflush(f);
if (ferror(f)) {
- log_error("Failed to write unit file %s: %m", unit);
+ log_error("Failed to write unit file %s: %m", p);
- lnk = strjoin(arg_dest, "/" SPECIAL_LOCAL_FS_TARGET ".requires/", unit, NULL);
- if (!lnk)
- return log_oom();
+ if (post) {
+ lnk = strjoin(arg_dest, "/", post, ".requires/", unit, NULL);
+ if (!lnk)
+ return log_oom();
- mkdir_parents_label(lnk, 0755);
- if (symlink(unit, lnk) < 0) {
- log_error("Failed to create symlink %s: %m", lnk);
- return -errno;
+ mkdir_parents_label(lnk, 0755);
+ if (symlink(p, lnk) < 0) {
+ log_error("Failed to create symlink %s: %m", lnk);
+ return -errno;
+ }
unsigned home_nr = (unsigned) -1, srv_nr = (unsigned )-1;
struct udev_list_entry *first, *item;
struct udev_device *parent = NULL;
unsigned home_nr = (unsigned) -1, srv_nr = (unsigned )-1;
struct udev_list_entry *first, *item;
struct udev_device *parent = NULL;
e = udev_enumerate_new(udev);
if (!e)
e = udev_enumerate_new(udev);
if (!e)
first = udev_enumerate_get_list_entry(e);
udev_list_entry_foreach(item, first) {
_cleanup_udev_device_unref_ struct udev_device *q;
first = udev_enumerate_get_list_entry(e);
udev_list_entry_foreach(item, first) {
_cleanup_udev_device_unref_ struct udev_device *q;
if (!node)
return log_oom();
if (!node)
return log_oom();
- r = verify_gpt_partition(node, &type_id, &nr, &fstype);
- if (r < 0) {
+ k = verify_gpt_partition(node, &type_id, &nr, &fstype);
+ if (k < 0) {
/* skip child devices which are not detected properly */
/* skip child devices which are not detected properly */
- log_error("Failed to verify GPT partition %s: %s", node, strerror(-r));
- return r;
+
+ log_error("Failed to verify GPT partition %s: %s", node, strerror(-k));
+ r = k;
+ continue;
- if (sd_id128_equal(type_id, GPT_SWAP))
- add_swap(node, fstype);
+ if (sd_id128_equal(type_id, GPT_SWAP)) {
+
+ k = add_swap(node, fstype);
+ if (k < 0)
+ r = k;
- else if (sd_id128_equal(type_id, GPT_HOME)) {
+ } else if (sd_id128_equal(type_id, GPT_HOME)) {
/* We only care for the first /home partition */
if (home && nr >= home_nr)
/* We only care for the first /home partition */
if (home && nr >= home_nr)
- if (home && home_fstype)
- add_mount("home", home, "/home", home_fstype, "Home Partition");
+ if (home && home_fstype) {
+ k = add_mount("home", home, "/home", home_fstype, NULL, "Home Partition", SPECIAL_LOCAL_FS_TARGET);
+ if (k < 0)
+ r = k;
+ }
- if (srv && srv_fstype)
- add_mount("srv", srv, "/srv", srv_fstype, "Server Data Partition");
+ if (srv && srv_fstype) {
+ k = add_mount("srv", srv, "/srv", srv_fstype, NULL, "Server Data Partition", SPECIAL_LOCAL_FS_TARGET);
+ if (k < 0)
+ r = k;
+ }
-int main(int argc, char *argv[]) {
- _cleanup_udev_unref_ struct udev *udev = NULL;
- _cleanup_free_ char *node = NULL;
- dev_t devno;
- int r = 0;
+static int parse_proc_cmdline_item(const char *key, const char *value) {
+ int r;
- if (argc > 1 && argc != 4) {
- log_error("This program takes three or no arguments.");
- return EXIT_FAILURE;
- }
- if (argc > 1)
- arg_dest = argv[3];
+ if (STR_IN_SET(key, "systemd.gpt_auto", "rd.systemd.gpt_auto") && value) {
- log_set_target(LOG_TARGET_SAFE);
- log_parse_environment();
- log_open();
+ r = parse_boolean(value);
+ if (r < 0)
+ log_warning("Failed to parse gpt-auto switch %s. Ignoring.", value);
- if (in_initrd()) {
- log_debug("In initrd, exiting.");
- return EXIT_SUCCESS;
+ } else if (streq(key, "root") && value) {
+
+ /* Disable root disk logic if there's a root= value
+ * specified (unless it happens to be "gpt-auto") */
+
+ arg_root_enabled = streq(value, "gpt-auto");
+
+ } else if (streq(key, "rw") && !value)
+ arg_root_rw = true;
+ else if (streq(key, "ro") && !value)
+ arg_root_rw = false;
+ else if (startswith(key, "systemd.gpt-auto.") || startswith(key, "rd.systemd.gpt-auto."))
+ log_warning("Unknown kernel switch %s. Ignoring.", key);
+
+ return 0;
+}
+
+static int add_root_mount(void) {
+
+#ifdef ENABLE_EFI
+ int r;
+
+ if (!is_efi_boot()) {
+ log_debug("Not a EFI boot, not creating root mount.");
+ return 0;
- if (detect_container(NULL) > 0) {
- log_debug("In a container, exiting.");
- return EXIT_SUCCESS;
+ r = efi_loader_get_device_part_uuid(NULL);
+ if (r == -ENOENT) {
+ log_debug("EFI loader partition unknown, exiting.");
+ return 0;
+ } else if (r < 0) {
+ log_error("Failed to read ESP partition UUID: %s", strerror(-r));
+ return r;
+ /* OK, we have an ESP partition, this is fantastic, so let's
+ * wait for a root device to show up. A udev rule will create
+ * the link for us under the right name. */
+
+ return add_mount(
+ "root",
+ "/dev/disk/by-id/gpt-auto-root",
+ in_initrd() ? "/sysroot" : "/",
+ NULL,
+ arg_root_rw ? "rw" : "ro",
+ "Root Partition",
+ in_initrd() ? SPECIAL_INITRD_ROOT_FS_TARGET : SPECIAL_LOCAL_FS_TARGET);
+#else
+ return 0;
+#endif
+}
+
+static int add_mounts(void) {
+ _cleanup_udev_unref_ struct udev *udev = NULL;
+ _cleanup_free_ char *node = NULL;
+ dev_t devno;
+ int r;
+
r = get_block_device("/", &devno);
if (r < 0) {
log_error("Failed to determine block device of root file system: %s", strerror(-r));
r = get_block_device("/", &devno);
if (r < 0) {
log_error("Failed to determine block device of root file system: %s", strerror(-r));
} else if (r == 0) {
log_debug("Root file system not on a (single) block device.");
} else if (r == 0) {
log_debug("Root file system not on a (single) block device.");
- if (!udev) {
- log_oom();
- return EXIT_FAILURE;
- }
+ if (!udev)
+ return log_oom();
r = devno_to_devnode(udev, devno, &node);
if (r < 0) {
log_error("Failed to determine block device node from major/minor: %s", strerror(-r));
r = devno_to_devnode(udev, devno, &node);
if (r < 0) {
log_error("Failed to determine block device node from major/minor: %s", strerror(-r));
}
log_debug("Root device %s.", node);
}
log_debug("Root device %s.", node);
r = verify_gpt_partition(node, NULL, NULL, NULL);
if (r < 0) {
log_error("Failed to verify GPT partition %s: %s", node, strerror(-r));
r = verify_gpt_partition(node, NULL, NULL, NULL);
if (r < 0) {
log_error("Failed to verify GPT partition %s: %s", node, strerror(-r));
}
if (r == 0) {
log_debug("Not a GPT disk, exiting.");
}
if (r == 0) {
log_debug("Not a GPT disk, exiting.");
+ return 0;
+ }
+
+ return enumerate_partitions(udev, devno);
+}
+
+int main(int argc, char *argv[]) {
+ int r = 0;
+
+ if (argc > 1 && argc != 4) {
+ log_error("This program takes three or no arguments.");
+ return EXIT_FAILURE;
+ }
+
+ if (argc > 1)
+ arg_dest = argv[3];
+
+ log_set_target(LOG_TARGET_SAFE);
+ log_parse_environment();
+ log_open();
+
+ umask(0022);
+
+ if (detect_container(NULL) > 0) {
+ log_debug("In a container, exiting.");
- r = enumerate_partitions(udev, devno);
- if (r < 0)
+ if (parse_proc_cmdline(parse_proc_cmdline_item) < 0)
+ if (!arg_enabled) {
+ log_debug("Disabled, exiting.");
+ return EXIT_SUCCESS;
+ }
+
+ if (arg_root_enabled)
+ r = add_root_mount();
+
+ if (!in_initrd()) {
+ int k;
+
+ k = add_mounts();
+ if (k < 0)
+ r = k;
+ }
+
+ return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
int efi_loader_get_device_part_uuid(sd_id128_t *u) {
_cleanup_free_ char *p = NULL;
int r, parsed[16];
int efi_loader_get_device_part_uuid(sd_id128_t *u) {
_cleanup_free_ char *p = NULL;
int r, parsed[16];
- unsigned i;
-
- assert(u);
r = efi_get_variable_string(EFI_VENDOR_LOADER, "LoaderDevicePartUUID", &p);
if (r < 0)
r = efi_get_variable_string(EFI_VENDOR_LOADER, "LoaderDevicePartUUID", &p);
if (r < 0)
&parsed[12], &parsed[13], &parsed[14], &parsed[15]) != 16)
return -EIO;
&parsed[12], &parsed[13], &parsed[14], &parsed[15]) != 16)
return -EIO;
- for (i = 0; i < ELEMENTSOF(parsed); i++)
- u->bytes[i] = parsed[i];
+ if (u) {
+ unsigned i;
+
+ for (i = 0; i < ELEMENTSOF(parsed); i++)
+ u->bytes[i] = parsed[i];
+ }