openzfs · robn · Nov 27, 2025
diff --git a/include/Makefile.am b/include/Makefile.am
@@ -123,7 +123,6 @@ COMMON_H = \
 	sys/zcp_set.h \
 	sys/zfeature.h \
 	sys/zfs_acl.h \
-	sys/zfs_bootenv.h \
 	sys/zfs_chksum.h \
 	sys/zfs_context.h \
 	sys/zfs_debug.h \

diff --git a/include/libzfsbootenv.h b/include/libzfsbootenv.h
@@ -12,6 +12,7 @@
 
 /*
  * Copyright 2020 Toomas Soome <tsoome@me.com>
+ * Copyright (c) 2025, Rob Norris <robn@despairlabs.com>
  */
 
 #ifndef _LIBZFSBOOTENV_H
@@ -36,6 +37,8 @@ _LIBZFSBOOTENV_H int lzbe_set_boot_device(const char *, lzbe_flags_t,
     const char *);
 _LIBZFSBOOTENV_H int lzbe_get_boot_device(const char *, char **);
 _LIBZFSBOOTENV_H int lzbe_bootenv_print(const char *, const char *, FILE *);
+_LIBZFSBOOTENV_H const char *lzbe_loader_get(void);
+_LIBZFSBOOTENV_H int lzbe_loader_set(const char *, size_t);
 
 #ifdef __cplusplus
 }

diff --git a/include/os/freebsd/Makefile.am b/include/os/freebsd/Makefile.am
@@ -82,7 +82,6 @@ noinst_HEADERS = \
 	%D%/zfs/sys/freebsd_event.h \
 	%D%/zfs/sys/trace_zfs.h \
 	%D%/zfs/sys/vdev_os.h \
-	%D%/zfs/sys/zfs_bootenv_os.h \
 	%D%/zfs/sys/zfs_context_os.h \
 	%D%/zfs/sys/zfs_ctldir.h \
 	%D%/zfs/sys/zfs_debug_os.h \

diff --git a/include/os/freebsd/zfs/sys/zfs_bootenv_os.h b/include/os/freebsd/zfs/sys/zfs_bootenv_os.h
diff --git a/include/os/linux/Makefile.am b/include/os/linux/Makefile.am
@@ -38,7 +38,6 @@ kernel_sys_HEADERS = \
 	%D%/zfs/sys/trace_zil.h \
 	%D%/zfs/sys/trace_zio.h \
 	%D%/zfs/sys/trace_zrlock.h \
-	%D%/zfs/sys/zfs_bootenv_os.h \
 	%D%/zfs/sys/zfs_context_os.h \
 	%D%/zfs/sys/zfs_ctldir.h \
 	%D%/zfs/sys/zfs_debug_os.h \

diff --git a/include/os/linux/zfs/sys/zfs_bootenv_os.h b/include/os/linux/zfs/sys/zfs_bootenv_os.h
diff --git a/include/sys/fs/zfs.h b/include/sys/fs/zfs.h
@@ -32,6 +32,7 @@
  * Copyright (c) 2021, Colm Buckley <colm@tuatha.org>
  * Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
  * Copyright (c) 2024, Klara, Inc.
+ * Copyright (c) 2025, Rob Norris <robn@despairlabs.com>
  */
 
 #ifndef	_SYS_FS_ZFS_H
@@ -2003,6 +2004,41 @@ enum zio_encrypt {
 	    ZFS_XA_NS_PREFIX_MATCH(LINUX_TRUSTED, name) || \
 	    ZFS_XA_NS_PREFIX_MATCH(LINUX_USER, name))
 
+
+/*
+ * Boot environment support. The vdev environment block is accessed with the
+ * ZFS_IOC_GET_BOOTENV and ZFS_IOC_SET_BOOTENV calls. libzfsbootenv uses these
+ * internally, and is the preferred way to work with boot environments, but
+ * these defines are provided here to assist bootloaders and tools that want to
+ * do their own thing.
+ */
+
+#define	ZFS_BE_VERSION		"version"
+enum zfs_bootenv_version {
+	ZFS_BE_VERSION_GRUBENV	= 0,	/* GRUB "grubenv" file */
+	ZFS_BE_VERSION_NVLIST	= 1,	/* arbitrary packed nvlist */
+};
+
+/* nvlist key for GRUB "grubenv" string */
+#define	ZFS_BE_GRUB_ENVMAP	"grub:envmap"
+
+/*
+ * Keys in NVLIST bootenvs should be prefixed with a loader-specific string,
+ * allowing the envblock to support multiple loaders.
+ *
+ * This is the list of known loader prefixes.
+ */
+#define	ZFS_BE_LOADER_FREEBSD	"freebsd"
+#define	ZFS_BE_LOADER_ILLUMOS	"illumos"
+
+/*
+ * Common bootenv keys, to be combined with the loader prefix. New loaders are
+ * encouraged to use these where appropriate to assist cross-platform interop.
+ */
+#define	ZFS_BE_BOOTONCE		"bootonce"
+#define	ZFS_BE_BOOTONCE_USED	"bootonce-used"
+#define	ZFS_BE_NVSTORE		"nvstore"
+
 #ifdef	__cplusplus
 }
 #endif

diff --git a/include/sys/vdev_impl.h b/include/sys/vdev_impl.h
@@ -503,26 +503,6 @@ typedef struct vdev_phys {
 	zio_eck_t	vp_zbt;
 } vdev_phys_t;
 
-typedef enum vbe_vers {
-	/*
-	 * The bootenv file is stored as ascii text in the envblock.
-	 * It is used by the GRUB bootloader used on Linux to store the
-	 * contents of the grubenv file. The file is stored as raw ASCII,
-	 * and is protected by an embedded checksum. By default, GRUB will
-	 * check if the boot filesystem supports storing the environment data
-	 * in a special location, and if so, will invoke filesystem specific
-	 * logic to retrieve it. This can be overridden by a variable, should
-	 * the user so desire.
-	 */
-	VB_RAW = 0,
-
-	/*
-	 * The bootenv file is converted to an nvlist and then packed into the
-	 * envblock.
-	 */
-	VB_NVLIST = 1
-} vbe_vers_t;
-
 typedef struct vdev_boot_envblock {
 	uint64_t	vbe_version;
 	char		vbe_bootenv[VDEV_PAD_SIZE - sizeof (uint64_t) -

diff --git a/include/sys/zfs_bootenv.h b/include/sys/zfs_bootenv.h
diff --git a/lib/libzfsbootenv/Makefile.am b/lib/libzfsbootenv/Makefile.am
@@ -5,10 +5,10 @@ lib_LTLIBRARIES += libzfsbootenv.la
 CPPCHECKTARGETS += libzfsbootenv.la
 
 libzfsbootenv_la_CPPFLAGS  = $(AM_CPPFLAGS)
-libzfsbootenv_la_CPPFLAGS += -I$(srcdir)/include/os/@ac_system_l@/zfs
 
 dist_libzfsbootenv_la_SOURCES = \
 	%D%/lzbe_device.c \
+	%D%/lzbe_loader.c \
 	%D%/lzbe_pair.c \
 	%D%/lzbe_util.c
 
@@ -22,7 +22,7 @@ if !ASAN_ENABLED
 libzfsbootenv_la_LDFLAGS += -Wl,-z,defs
 endif
 
-libzfsbootenv_la_LDFLAGS += -version-info 1:0:0
+libzfsbootenv_la_LDFLAGS += -version-info 2:0:1
 
 pkgconfig_DATA += %D%/libzfsbootenv.pc
 

diff --git a/lib/libzfsbootenv/libzfsbootenv.abi b/lib/libzfsbootenv/libzfsbootenv.abi
@@ -8,6 +8,8 @@
     <elf-symbol name='lzbe_add_pair' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='lzbe_bootenv_print' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='lzbe_get_boot_device' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
+    <elf-symbol name='lzbe_loader_get' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
+    <elf-symbol name='lzbe_loader_set' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='lzbe_nvlist_free' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='lzbe_nvlist_get' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='lzbe_nvlist_set' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
@@ -225,6 +227,9 @@
       <parameter type-id='857bb57e'/>
       <return type-id='95e97e5e'/>
     </function-decl>
+    <function-decl name='lzbe_loader_get' mangled-name='lzbe_loader_get' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='lzbe_loader_get'>
+      <return type-id='80f4b756'/>
+    </function-decl>
     <function-decl name='nvlist_free' visibility='default' binding='global' size-in-bits='64'>
       <parameter type-id='5ce45b60'/>
       <return type-id='48b5725f'/>
@@ -314,6 +319,13 @@
       <return type-id='95e97e5e'/>
     </function-decl>
   </abi-instr>
+  <abi-instr address-size='64' path='lib/libzfsbootenv/lzbe_loader.c' language='LANG_C99'>
+    <function-decl name='lzbe_loader_set' mangled-name='lzbe_loader_set' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='lzbe_loader_set'>
+      <parameter type-id='80f4b756' name='loader'/>
+      <parameter type-id='b59d7dce' name='len'/>
+      <return type-id='95e97e5e'/>
+    </function-decl>
+  </abi-instr>
   <abi-instr address-size='64' path='lib/libzfsbootenv/lzbe_pair.c' language='LANG_C99'>
     <type-decl name='short int' size-in-bits='16' id='a2185560'/>
     <type-decl name='unsigned char' size-in-bits='8' id='002ac4a6'/>