On Sun, 13 Mar 2022 19:03:20 -0700 Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote: > > > On 3/13/22 18:54, Masami Hiramatsu wrote: > > Add a description how to embed the bootconfig file into kernel. > > > > Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > > --- > > Changes in v2: > > - Corrected the text accoding to Randy's suggestion. > > - Do not reccomend to use relative path for CONFIG_EMBED_BOOT_CONFIG_FILE. > > --- > > Documentation/admin-guide/bootconfig.rst | 30 +++++++++++++++++++++++++++--- > > 1 file changed, 27 insertions(+), 3 deletions(-) > > > > diff --git a/Documentation/admin-guide/bootconfig.rst b/Documentation/admin-guide/bootconfig.rst > > index a1860fc0ca88..1af1a172fdd4 100644 > > --- a/Documentation/admin-guide/bootconfig.rst > > +++ b/Documentation/admin-guide/bootconfig.rst > > @@ -158,9 +158,15 @@ Each key-value pair is shown in each line with following style:: > > Boot Kernel With a Boot Config > > ============================== > > > > -Since the boot configuration file is loaded with initrd, it will be added > > -to the end of the initrd (initramfs) image file with padding, size, > > -checksum and 12-byte magic word as below. > > +There are two options to boot the kernel with bootconfig: attaching the > > +bootconfig to the initrd image or embedding it in the kernel itself. > > + > > +Attaching a Boot Config to Initrd > > +--------------------------------- > > + > > +Since the boot configuration file is loaded with initrd by default, > > +it will be added to the end of the initrd (initramfs) image file with > > +padding, size, checksum and 12-byte magic word as below. > > > > [initrd][bootconfig][padding][size(le32)][checksum(le32)][#BOOTCONFIG\n] > > > > @@ -196,6 +202,24 @@ To remove the config from the image, you can use -d option as below:: > > Then add "bootconfig" on the normal kernel command line to tell the > > kernel to look for the bootconfig at the end of the initrd file. > > > > +Embedding a Boot Config into Kernel > > +----------------------------------- > > + > > +If you can not use initrd, you can also embed the bootconfig file in the > > +kernel by Kconfig options. In this case, you need to recompile the kernel > > +with the following configs:: > > + > > + COFNIG_EMBED_BOOT_CONFIG=y > > CONFIG_ Oops, it's a typo... > > > + CONFIG_EMBED_BOOT_CONFIG_FILE="/PATH/TO/BOOTCONFIG/FILE" > > + > > +``CONFIG_EMBED_BOOT_CONFIG_FILE`` requires a correct absolute path to > > +the bootconfig file. The kernel will embed it as the default bootconfig. > > + > > +Just as when attaching the bootconfig to the initrd, you need ``bootconfig`` > > +option to the kernel command line to enable the embedded bootconfig. > > on the OK. Thank you! > > preferably. > > > + > > +Note that even if you set this option, you can override the embedded > > +bootconfig by another bootconfig which attached to the initrd. > > > > Kernel parameters via Boot Config > > ================================= > > > > thanks. > -- > ~Randy -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
