flash-kernel - put kernel and initramfs in boot location
flash-kernel [--supported] [--force] [kvers]
flash-kernel is a script which will put the kernel and initramfs
in the boot location of embedded devices that don't load the kernel and
initramfs directly from /boot. flash-kernel supports devices that boot from
flash memory (hence the name) as well as some devices that require a special
boot image on the disk.
Optionally, it can be passed a version of the kernel to flash;
only the highest version will be flashed and other versions will be ignored
unless the --force option is used. Kernel and initrd are read from
/boot.
Note that when the --force the kernel can be overwritten with the
current version whenever a package is installed which changes the kernel,
initramfs etc. Therefore this is only really useful for one-off testing.
Prior to flashing the kernel, a check is performed to verify that
the subarchitectures of the machine and the image to be flashed match. Valid
filenames for images to flash are suffixed with the subarchitecture.
If the --supported option is used, flash-kernel will test to see
if the hardware is supported, and return a true or false value.
- FK_MACHINE
- Specify a specific machine, overriding the autodetection, also see the
description of /etc/flash-kernel/machine below. Can be set to
`none' to disable flash-kernel. This can be used when installing
flash-kernel into a chroot, for example while preparing a filesystem
image. WARNING: Take great care when running flash-kernel in a chroot,
since the choice of machine may cause host filesystem partitions to
be mounted and modified.
- FK_IGNORE_EFI
- Skip EFI detection when this variable is set to `yes'. Normally,
flash-kernel will abort if it detects that the system is running in EFI
mode.
- /usr/share/flash-kernel/db/all.db
- The database of machines which flash-kernel knows about. See
/usr/share/doc/flash-kernel/README.gz For information on the
database fields.
- /etc/default/flash-kernel
- may contain the following variables:
- LINUX_KERNEL_CMDLINE, which is used by bootscripts to set kernel
command line options, overriding the firmwares defaults (e.g. u-boot's
${bootargs}).
- LINUX_KERNEL_CMDLINE_DEFAULTS, which is used by bootscripts to set
kernel options which should be overrideable by the firmware's defaults
(e.g. u-boot's ${bootargs}).
- NO_CREATE_DOT_BAK_FILES, which if set to "true" or
"yes" will prevent flash-kernel from creating backup
".bak" versions of kernel, initrd, and dtb files when installing
a new version. The default is to create such backups to aid in recovery
from failed updates.
- MTD_BACKUP_DIR, which if set, names a directory to which
flash-kernel will write copies of files which would not normally be
accessible in the regular filesystem (either written to a raw flash
partition or to a firmware partition which is not normally mounted). If
unset defaults to /var/backups/flash-kernel. Set to
"none" to disable.
- /etc/flash-kernel/db
- Local overrides to the database of machines
- /etc/flash-kernel/machine
- If present this can be used to override the machine autodetection. The
contents must be a string which matches an entry in the database. Or
`none' to disable flash-kernel. /etc/flash-kernel/ignore-efi If
present, the contents of this file are used to set the value of the
FK_IGNORE_EFI environment variable.
Martin Michlmayr <tbm@cyrius.com>