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author | Scott Rifenbark <scott.m.rifenbark@intel.com> | 2012-01-05 09:52:18 -0600 |
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committer | Richard Purdie <richard.purdie@linuxfoundation.org> | 2012-01-06 12:13:12 +0000 |
commit | 03df4ce0938673b40eeb13bd7f52be05285ce1fe (patch) | |
tree | b2b268da6bf885bbe458278c879fd505f9bb7437 /documentation | |
parent | 01d5729e13b8688b7238bf763dfd808df5808005 (diff) | |
download | ast2050-yocto-poky-03df4ce0938673b40eeb13bd7f52be05285ce1fe.zip ast2050-yocto-poky-03df4ce0938673b40eeb13bd7f52be05285ce1fe.tar.gz |
documentation/poky-ref-manual/ref-variables.xml: image size glossary
I added three new glossary entries for how the build process
figures out the image size. Entries are for IMAGE_ROOTFS_SIZE,
IMAGE_OVERHEAD_FACTOR, and IMAGE_ROOTFS_EXTRA_SPACE.
I still need to create a usage section for this topic.
Likely this will be in the development manual in a new chapter
I am thinking about.
Fixes [YOCTO #1110] partially.
(From yocto-docs rev: ec6b9d77d10a95f0a2d460dca3cf8eab5dfbf0c0)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'documentation')
-rw-r--r-- | documentation/poky-ref-manual/ref-variables.xml | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/documentation/poky-ref-manual/ref-variables.xml b/documentation/poky-ref-manual/ref-variables.xml index 4da61ff..128f27d 100644 --- a/documentation/poky-ref-manual/ref-variables.xml +++ b/documentation/poky-ref-manual/ref-variables.xml @@ -510,6 +510,87 @@ </glossdef> </glossentry> + <glossentry id='var-IMAGE_OVERHEAD_FACTOR'><glossterm>IMAGE_OVERHEAD_FACTOR</glossterm> + <glossdef> + <para> + Defines a multiplier that the build system might apply to the initial image + size to create free disk space in the image as overhead. + By default, the build process uses a multiplier of 1.3 for this variable. + This default value results in 30% free disk space added to the image when this + method is used to determine the final generated image size. + See <filename><link linkend='var-IMAGE_ROOTFS_SIZE'>IMAGE_ROOTFS_SIZE</link></filename> + for information on how the build system determines the overall image size. + </para> + + <para> + The default 30% free disk space typically gives the image enough room to boot + and allows for basic post installs while still leaving a small amount of + free disk space. + If 30% free space is inadequate, you can increase the default value. + For example, the following setting gives you 50% free space added to the image: + <literallayout class='monospaced'> + IMAGE_OVERHEAD_FACTOR = "1.5" + </literallayout> + </para> + + <para> + Alternatively, you can ensure a specific amount of free disk space is added + to the image by using + <filename><link linkend='var-IMAGE_ROOTFS_EXTRA_SPACE'>IMAGE_ROOTFS_EXTRA_SPACE</link></filename> + the variable. + </para> + </glossdef> + </glossentry> + + <glossentry id='var-IMAGE_ROOTFS_EXTRA_SPACE'><glossterm>IMAGE_ROOTFS_EXTRA_SPACE</glossterm> + <glossdef> + <para> + Defines additional free disk space created in the image in Kbytes. + By default, this variable is set to "0". + This free disk space is added to the image after the build system determines + the image size as described in + <filename><link linkend='var-IMAGE_ROOTFS_SIZE'>IMAGE_ROOTFS_SIZE</link></filename>. + </para> + + <para> + This variable is particularly useful when you want to ensure that a + specific amount of free disk space is available on a device after an image + is installed and running. + For example, to be sure 5 Gbytes of free disk space is available, set the + variable as follows: + <literallayout class='monospaced'> + IMAGE_ROOTFS_EXTRA_SPACE = "5242880" + </literallayout> + </para> + </glossdef> + </glossentry> + + <glossentry id='var-IMAGE_ROOTFS_SIZE'><glossterm>IMAGE_ROOTFS_SIZE</glossterm> + <glossdef> + <para> + Defines the size in Kbytes for the generated image. + The Yocto Project build system determines the final size for the generated + image using an algorithm that takes into account the initial disk space used + for the generated image, a requested size for the image, and requested + additional free disk space to be added to the image. + Programatically, the build system determines the final size of the + generated image as follows: + <literallayout class='monospaced'> + if (du * overhead) < IMAGE_ROOTFS_SIZE: + IMAGE_ROOTFS_SIZE = IMAGE_ROOTFS_SIZE + xspace + else: + IMAGE_ROOTFS_SIZE = (du * overhead) + xspace + </literallayout> + In the above example, <filename>overhead</filename> is defined by the + <filename><link linkend='var-IMAGE_OVERHEAD_FACTOR'>IMAGE_OVERHEAD_FACTOR</link></filename> + variable, <filename>xspace</filename> is defined by the + <filename><link linkend='var-IMAGE_ROOTFS_EXTRA_SPACE'>IMAGE_ROOTFS_EXTRA_SPACE</link></filename> + variable, and <filename>du</filename> is the results of the disk usage command + on the initially generated image. + </para> + </glossdef> + </glossentry> + <glossentry id='var-INC_PR'><glossterm>INC_PR</glossterm> <glossdef> <para>Defines the Package revision. |