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-rw-r--r--doc/guix.texi48
1 files changed, 25 insertions, 23 deletions
diff --git a/doc/guix.texi b/doc/guix.texi
index 5129b998bd..5eee40fc3c 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -9210,20 +9210,31 @@ This is a string specifying the type of the file system---e.g.,
This designates the place where the file system is to be mounted.
@item @code{device}
-This names the ``source'' of the file system. By default it is the name
-of a node under @file{/dev}, but its meaning depends on the @code{title}
-field described below.
+This names the ``source'' of the file system. It can be one of three
+things: a file system label, a file system UUID, or the name of a
+@file{/dev} node. Labels and UUIDs offer a way to refer to file
+systems without having to hard-code their actual device
+name@footnote{Note that, while it is tempting to use
+@file{/dev/disk/by-uuid} and similar device names to achieve the same
+result, this is not recommended: These special device nodes are created
+by the udev daemon and may be unavailable at the time the device is
+mounted.}.
-@item @code{title} (default: @code{'device})
-This is a symbol that specifies how the @code{device} field is to be
-interpreted.
+@findex file-system-label
+File system labels are created using the @code{file-system-label}
+procedure, UUIDs are created using @code{uuid}, and @file{/dev} node are
+plain strings. Here's an example of a file system referred to by its
+label, as shown by the @command{e2label} command:
-When it is the symbol @code{device}, then the @code{device} field is
-interpreted as a file name; when it is @code{label}, then @code{device}
-is interpreted as a file system label name; when it is @code{uuid},
-@code{device} is interpreted as a file system unique identifier (UUID).
+@example
+(file-system
+ (mount-point "/home")
+ (type "ext4")
+ (device (file-system-label "my-home")))
+@end example
-UUIDs may be converted from their string representation (as shown by the
+@findex uuid
+UUIDs are converted from their string representation (as shown by the
@command{tune2fs -l} command) using the @code{uuid} form@footnote{The
@code{uuid} form expects 16-byte UUIDs as defined in
@uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}. This is the
@@ -9235,22 +9246,13 @@ like this:
(file-system
(mount-point "/home")
(type "ext4")
- (title 'uuid)
(device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
@end example
-The @code{label} and @code{uuid} options offer a way to refer to file
-systems without having to hard-code their actual device
-name@footnote{Note that, while it is tempting to use
-@file{/dev/disk/by-uuid} and similar device names to achieve the same
-result, this is not recommended: These special device nodes are created
-by the udev daemon and may be unavailable at the time the device is
-mounted.}.
-
-However, when the source of a file system is a mapped device (@pxref{Mapped
+When the source of a file system is a mapped device (@pxref{Mapped
Devices}), its @code{device} field @emph{must} refer to the mapped
-device name---e.g., @file{/dev/mapper/root-partition}---and consequently
-@code{title} must be set to @code{'device}. This is required so that
+device name---e.g., @file{"/dev/mapper/root-partition"}.
+This is required so that
the system knows that mounting the file system depends on having the
corresponding device mapping established.