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Reference, Up: Creating System Images [Contents][Index]
Let’s say you would like to create an MBR image with three distinct partitions:
%simple-os
operating-system.
You would then write the following image definition in a
my-image.scm
file for instance.
(use-modules (gnu) (gnu image) (gnu tests) (gnu system image) (guix gexp)) (define MiB (expt 2 20)) (image (format 'disk-image) (operating-system %simple-os) (partitions (list (partition (size (* 40 MiB)) (offset (* 1024 1024)) (label "GNU-ESP") (file-system "vfat") (flags '(esp)) (initializer (gexp initialize-efi-partition))) (partition (size (* 50 MiB)) (label "DATA") (file-system "ext4") (initializer #~(lambda* (root . rest) (mkdir root) (call-with-output-file (string-append root "/data") (lambda (port) (format port "my-data")))))) (partition (size 'guess) (label root-label) (file-system "ext4") (flags '(boot)) (initializer (gexp initialize-root-partition))))))
Note that the first and third partitions use generic initializers
procedures, initialize-efi-partition and initialize-root-partition
respectively. The initialize-efi-partition installs a GRUB EFI loader
that is loading the GRUB bootloader located in the root partition. The
initialize-root-partition instantiates a complete system as defined by
the %simple-os
operating-system.
You can now run:
guix system image my-image.scm
to instantiate the image
definition. That produces a disk image
which has the expected structure:
$ parted $(guix system image my-image.scm) print … Model: (file) Disk /gnu/store/yhylv1bp5b2ypb97pd3bbhz6jk5nbhxw-disk-image: 1714MB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags: Number Start End Size Type File system Flags 1 1049kB 43.0MB 41.9MB primary fat16 esp 2 43.0MB 95.4MB 52.4MB primary ext4 3 95.4MB 1714MB 1619MB primary ext4 boot
The size of the boot
partition has been inferred to 1619MB
so that it is large enough to host the %simple-os
operating-system.
You can also use existing image
record definitions and inherit
from them to simplify the image
definition. The (gnu
system image)
module provides the following image
definition
variables.
A MBR disk-image composed of two partitions: a 64 bits ESP partition and
a ROOT boot partition. This image can be used on most x86_64
and
i686
machines, supporting BIOS or UEFI booting.
Same as efi-disk-image
but with a 32 bits EFI partition.
An ISO-9660 image composed of a single bootable partition. This image
can also be used on most x86_64
and i686
machines.
A Docker image that can be used to spawn a Docker container.
Using the efi-disk-image
we can simplify our previous
image
declaration this way:
(use-modules (gnu) (gnu image) (gnu tests) (gnu system image) (guix gexp) (ice-9 match)) (define MiB (expt 2 20)) (define data (partition (size (* 50 MiB)) (label "DATA") (file-system "ext4") (initializer #~(lambda* (root . rest) (mkdir root) (call-with-output-file (string-append root "/data") (lambda (port) (format port "my-data"))))))) (image (inherit efi-disk-image) (operating-system %simple-os) (partitions (match (image-partitions efi-disk-image) ((esp root) (list esp data root)))))
This will give the exact same image
instantiation but the
image
declaration is simpler.
Next: image-type Reference, Previous: image
Reference, Up: Creating System Images [Contents][Index]