image-types_uboot: Package a self contained netboot image

Create a cpio containing the base read-only image, and create a
single combined initramfs image consisting of the image-rofs
and the existing initramfs.

There has been a desire to have a self contained netboot image present
for developer testing and experimentation.   The init script already
supports having the rofs layer sourced from a file packaged into the
initramfs, and will use it if found.

While this image will not fit in the current flash layout in
the initrd space, it will load over the network.  This method
leaves the squashfs compressed in RAM, decompreses is invoked as
needed at runtime, trading boot time and memory space for runtime
decompress on demand.  This will also give similar file access
overheads and performance to reading the data from flash.

Because the rofs is already compressed with xz compression,
don't try to compress this cpio (the cpio packaging adds about 40
bytes of ascii before and after, plus some alignment padding).
Because the kernel requires uncompressed cpios to appear on a
4-byte boundary with 0 byte fill between archives, place this
cpio first in the combined image.

Signed-off-by: Milton Miller <>
1 file changed
tree: 25a55bf10ec8793be78163c822b6e1b5602cd8b0
  1. meta-openbmc-bsp/
  2. meta-openbmc-machines/
  3. meta-phosphor/
  4. yocto-poky/
  5. .gitignore
  6. .templateconf
  7. openbmc-env


Build Status


OpenBMC uses Yocto/Open-Embedded for a build system, which supports an out-of-tree build. It is recommended that you create an empty directory somewhere to hold the build. This directory will get big.

On Ubuntu 14.04 the following packages are required to build the default target

sudo apt-get install -y git build-essential libsdl1.2-dev texinfo gawk chrpath diffstat

On Fedora 23 the following packages are required to build the default target:

sudo dnf install -y git patch diffstat texinfo chrpath SDL-devel bitbake
sudo dnf groupinstall "C Development Tools and Libraries"

To start a build:

cd <builddir>
. <repodir>/openbmc-env
bitbake obmc-phosphor-image