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-rw-r--r--doc/guix.texi34
1 files changed, 27 insertions, 7 deletions
diff --git a/doc/guix.texi b/doc/guix.texi
index 50c4984d71..617b8463e3 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -40982,8 +40982,8 @@ QEMU monitor and the VM.
@cindex image, creating disk images
The @code{image} command can produce various image types. The image
type can be selected using the @option{--image-type} option. It
-defaults to @code{mbr-raw}. When its value is @code{iso9660}, the
-@option{--label} option can be used to specify a volume ID with
+defaults to @code{mbr-hybrid-raw}. When its value is @code{iso9660},
+the @option{--label} option can be used to specify a volume ID with
@code{image}. By default, the root file system of a disk image is
mounted non-volatile; the @option{--volatile} option can be provided to
make it volatile instead. When using @code{image}, the bootloader
@@ -41001,8 +41001,8 @@ qemu-system-x86_64 -enable-kvm -hda /tmp/my-image.qcow2 -m 1000 \
-bios $(guix build ovmf)/share/firmware/ovmf_x64.bin
@end example
-When using the @code{mbr-raw} image type, a raw disk image is produced;
-it can be copied as is to a USB stick, for instance. Assuming
+When using the @code{mbr-hybrid-raw} image type, a raw disk image is
+produced; it can be copied as is to a USB stick, for instance. Assuming
@code{/dev/sdc} is the device corresponding to a USB stick, one can copy
the image to it using the following command:
@@ -41139,7 +41139,7 @@ of the image.
For the @code{image} action, create an image with given @var{type}.
When this option is omitted, @command{guix system} uses the
-@code{mbr-raw} image type.
+@code{mbr-hybrid-raw} image type.
@cindex ISO-9660 format
@cindex CD image format
@@ -45347,7 +45347,7 @@ then directly boot from it, without any kind of installation procedure.
The @command{guix system image} command is able to turn an operating
system definition into a bootable image. This command supports
-different image types, such as @code{mbr-raw}, @code{iso9660} and
+different image types, such as @code{mbr-hybrid-raw}, @code{iso9660} and
@code{docker}. Any modern @code{x86_64} machine will probably be able
to boot from an @code{iso9660} image. However, there are a few machines
out there that require specific image types. Those machines, in general
@@ -45611,8 +45611,24 @@ from them to simplify the @code{image} definition. The @code{(gnu
system image)} module provides the following @code{image} definition
variables.
+@defvar mbr-disk-image
+An MBR disk-image composed of a single ROOT partition. The ROOT
+partition starts at a 1@tie{}MiB offset so that the bootloader can
+install itself in the post-MBR gap.
+@end defvar
+
+@defvar mbr-hybrid-disk-image
+An MBR disk-image composed of two partitions: a 64 bits ESP partition
+and a ROOT boot partition. The ESP partition starts at a 1@tie{}MiB
+offset so that a BIOS compatible bootloader can install itself in the
+post-MBR gap. The image can be used by @code{x86_64} and @code{i686}
+machines supporting only legacy BIOS booting. The ESP partition ensures
+that it can also be used by newer machines relying on UEFI booting,
+hence the @emph{hybrid} denomination.
+@end defvar
+
@defvar efi-disk-image
-A MBR disk-image composed of two partitions: a 64 bits ESP partition and
+A GPT disk-image composed of two partitions: a 64 bits ESP partition and
a ROOT boot partition. This image can be used on most @code{x86_64} and
@code{i686} machines, supporting BIOS or UEFI booting.
@end defvar
@@ -45703,6 +45719,10 @@ system image)} and the @code{(gnu system images @dots{})} modules.
Build an image based on the @code{mbr-disk-image} image.
@end defvar
+@defvar mbr-hybrid-raw-image-type
+Build an image based on the @code{mbr-hybrid-disk-image} image.
+@end defvar
+
@defvar efi-raw-image-type
Build an image based on the @code{efi-disk-image} image.
@end defvar