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Diffstat (limited to 'documentation/ref-manual/closer-look.xml')
-rw-r--r-- | documentation/ref-manual/closer-look.xml | 103 |
1 files changed, 71 insertions, 32 deletions
diff --git a/documentation/ref-manual/closer-look.xml b/documentation/ref-manual/closer-look.xml index bb7624c9e8..c05972e9ec 100644 --- a/documentation/ref-manual/closer-look.xml +++ b/documentation/ref-manual/closer-look.xml | |||
@@ -993,11 +993,13 @@ | |||
993 | 993 | ||
994 | <para> | 994 | <para> |
995 | The image generation process consists of several stages and | 995 | The image generation process consists of several stages and |
996 | depends on many variables. | 996 | depends on several tasks and variables. |
997 | The | 997 | The |
998 | <link linkend='ref-tasks-rootfs'><filename>do_rootfs</filename></link> | 998 | <link linkend='ref-tasks-rootfs'><filename>do_rootfs</filename></link> |
999 | task uses these key variables | 999 | task creates the root filesystem (file and directory structure) |
1000 | to help create the list of packages to actually install: | 1000 | for an image. |
1001 | This task uses several key variables to help create the list | ||
1002 | of packages to actually install: | ||
1001 | <itemizedlist> | 1003 | <itemizedlist> |
1002 | <listitem><para><link linkend='var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></link>: | 1004 | <listitem><para><link linkend='var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></link>: |
1003 | Lists out the base set of packages to install from | 1005 | Lists out the base set of packages to install from |
@@ -1017,23 +1019,34 @@ | |||
1017 | Determines the language(s) for which additional | 1019 | Determines the language(s) for which additional |
1018 | language support packages are installed. | 1020 | language support packages are installed. |
1019 | </para></listitem> | 1021 | </para></listitem> |
1022 | <listitem><para><link linkend='var-PACKAGE_INSTALL'><filename>PACKAGE_INSTALL</filename></link>: | ||
1023 | The final list of packages passed to the package manager | ||
1024 | for installation into the image. | ||
1025 | </para></listitem> | ||
1020 | </itemizedlist> | 1026 | </itemizedlist> |
1021 | </para> | 1027 | </para> |
1022 | 1028 | ||
1023 | <para> | 1029 | <para> |
1030 | With | ||
1031 | <link linkend='var-IMAGE_ROOTFS'><filename>IMAGE_ROOTFS</filename></link> | ||
1032 | pointing to the location of the filesystem under construction and | ||
1033 | the <filename>PACKAGE_INSTALL</filename> variable providing the | ||
1034 | final list of packages to install, the root file system is | ||
1035 | created. | ||
1036 | </para> | ||
1037 | |||
1038 | <para> | ||
1024 | Package installation is under control of the package manager | 1039 | Package installation is under control of the package manager |
1025 | (e.g. smart/rpm, opkg, or apt/dpkg) regardless of whether or | 1040 | (e.g. smart/rpm, opkg, or apt/dpkg) regardless of whether or |
1026 | not package management is enabled for the target. | 1041 | not package management is enabled for the target. |
1027 | At the end of the process, if package management is not | 1042 | At the end of the process, if package management is not |
1028 | enabled for the target, the package manager's data files | 1043 | enabled for the target, the package manager's data files |
1029 | are deleted from the root filesystem. | 1044 | are deleted from the root filesystem. |
1030 | </para> | 1045 | As part of the final stage of package installation, postinstall |
1031 | 1046 | scripts that are part of the packages are run. | |
1032 | <para> | 1047 | Any scripts that fail to run |
1033 | During image generation, the build system attempts to run | 1048 | on the build host are run on the target when the target system |
1034 | all post-installation scripts. | 1049 | is first booted. |
1035 | Any that fail to run on the build host are run on the | ||
1036 | target when the target system is first booted. | ||
1037 | If you are using a | 1050 | If you are using a |
1038 | <ulink url='&YOCTO_DOCS_DEV_URL;#creating-a-read-only-root-filesystem'>read-only root filesystem</ulink>, | 1051 | <ulink url='&YOCTO_DOCS_DEV_URL;#creating-a-read-only-root-filesystem'>read-only root filesystem</ulink>, |
1039 | all the post installation scripts must succeed during the | 1052 | all the post installation scripts must succeed during the |
@@ -1042,24 +1055,17 @@ | |||
1042 | </para> | 1055 | </para> |
1043 | 1056 | ||
1044 | <para> | 1057 | <para> |
1045 | During Optimization, optimizing processes are run across | 1058 | The final stages of the <filename>do_rootfs</filename> task |
1046 | the image. | 1059 | handle post processing. |
1047 | These processes include <filename>mklibs</filename> and | 1060 | Post processing includes creation of a manifest file and |
1048 | <filename>prelink</filename>. | 1061 | optimizations. |
1049 | The <filename>mklibs</filename> process optimizes the size | ||
1050 | of the libraries. | ||
1051 | A <filename>prelink</filename> process optimizes the dynamic | ||
1052 | linking of shared libraries to reduce start up time of | ||
1053 | executables. | ||
1054 | </para> | 1062 | </para> |
1055 | 1063 | ||
1056 | <para> | 1064 | <para> |
1057 | Along with writing out the root filesystem image, the | 1065 | The manifest file (<filename>.manifest</filename>) resides |
1058 | <filename>do_rootfs</filename> task creates a manifest file | 1066 | in the same directory as the root filesystem image. |
1059 | (<filename>.manifest</filename>) in the same directory as | 1067 | This file lists out, line-by-line, the installed packages. |
1060 | the root filesystem image that lists out, line-by-line, the | 1068 | The manifest file is useful for the |
1061 | installed packages. | ||
1062 | This manifest file is useful for the | ||
1063 | <link linkend='ref-classes-testimage*'><filename>testimage</filename></link> | 1069 | <link linkend='ref-classes-testimage*'><filename>testimage</filename></link> |
1064 | class, for example, to determine whether or not to run | 1070 | class, for example, to determine whether or not to run |
1065 | specific tests. | 1071 | specific tests. |
@@ -1069,21 +1075,54 @@ | |||
1069 | </para> | 1075 | </para> |
1070 | 1076 | ||
1071 | <para> | 1077 | <para> |
1072 | Part of the image generation process includes compressing the | 1078 | Optimizing processes run across the image include |
1073 | root filesystem image. | 1079 | <filename>mklibs</filename>, <filename>prelink</filename>, |
1074 | Compression is accomplished through several optimization | 1080 | and any other post-processing commands as defined by the |
1075 | routines designed to reduce the overall size of the image. | 1081 | <link linkend='var-ROOTFS_POSTPROCESS_COMMAND'><filename>ROOTFS_POSTPROCESS_COMMAND</filename></link> |
1082 | variable. | ||
1083 | The <filename>mklibs</filename> process optimizes the size | ||
1084 | of the libraries, while the | ||
1085 | <filename>prelink</filename> process optimizes the dynamic | ||
1086 | linking of shared libraries to reduce start up time of | ||
1087 | executables. | ||
1088 | </para> | ||
1089 | |||
1090 | <para> | ||
1091 | After the root filesystem is built, processing begins on | ||
1092 | the image through the <filename>do_image</filename> task. | ||
1093 | The build system runs any pre-processing commands as defined | ||
1094 | by the | ||
1095 | <link linkend='var-IMAGE_PREPROCESS_COMMAND'><filename>IMAGE_PREPROCESS_COMMAND</filename></link> | ||
1096 | variable. | ||
1097 | This variable specifies a list of functions to call before | ||
1098 | the OpenEmbedded build system creates the final image output | ||
1099 | files. | ||
1076 | </para> | 1100 | </para> |
1077 | 1101 | ||
1078 | <para> | 1102 | <para> |
1079 | After the root filesystem has been constructed, the image | 1103 | The <filename>do_image</filename> task dynamically creates |
1080 | generation process turns everything into an image file or | 1104 | other <filename>do_image_*</filename> tasks as needed, which |
1081 | a set of image files. | 1105 | include compressing the root filesystem image to reduce the |
1106 | overall size of the image. | ||
1107 | The process turns everything into an image file or a set of | ||
1108 | image files. | ||
1082 | The formats used for the root filesystem depend on the | 1109 | The formats used for the root filesystem depend on the |
1083 | <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link> | 1110 | <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link> |
1084 | variable. | 1111 | variable. |
1085 | </para> | 1112 | </para> |
1086 | 1113 | ||
1114 | <para> | ||
1115 | The final task involved in image creation is the | ||
1116 | <filename>do_image_complete</filename> task. | ||
1117 | This task completes the image by applying any image | ||
1118 | post processing as defined through the | ||
1119 | <link linkend='var-IMAGE_POSTPROCESS_COMMAND'><filename>IMAGE_POSTPROCESS_COMMAND</filename></link> | ||
1120 | variable. | ||
1121 | The variable specifies a list of functions to call once the | ||
1122 | OpenEmbedded build system has created the final image output | ||
1123 | files. | ||
1124 | </para> | ||
1125 | |||
1087 | <note> | 1126 | <note> |
1088 | The entire image generation process is run under Pseudo. | 1127 | The entire image generation process is run under Pseudo. |
1089 | Running under Pseudo ensures that the files in the root | 1128 | Running under Pseudo ensures that the files in the root |