68 lines
2.5 KiB
Plaintext
68 lines
2.5 KiB
Plaintext
Introduction
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------------
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Variants enable debian-cd to include extra functionality in a built
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image which is somewhat orthogonal to the usual DISKTYPE and ARCH
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configurations.
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Variants are enabled by setting the VARIANTS environment variable to a
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space separated list of the variants to enable or by passing the -V
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option (multiple times if desired) to the easy-build.sh script.
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Available Variants
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------------------
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* `xen' [i386, amd64 only]
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This variant includes a kernel and installer initrd which is
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compatible with the Xen hypervisor in `install.<arch>/xen' and
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includes matching kernel module .udebs as well as a suitable kernel
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.deb for installation into the final system.
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Implementation
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--------------
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Variants impact several aspects of the debian-cd infrastructure:
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environment variable
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--------------------
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The $VARIANTS environment variable is available to any scripts etc
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which are run as part of the build process and is a space separated
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list of the variants which are enabled.
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In particular this maybe used by the per-archtecture
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tools/boot/<distro>/boot-* scripts which make an image bootable on a
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particular architecure. To facilitate this
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tools/boot/<distro>/common.sh defines a function `variant_enabled'
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which takes a variant name as an argument and returns true if that
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variant is enabled.
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deb package lists
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-----------------
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A variant may wish to include extra .deb packages in the image. The
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package lists are preprocessed using `cpp' as part of the build
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process and a C-preprocessor variable `VARIANT_<x>' will be defined
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to 1 for each variant which is enabled.
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udeb package lists
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------------------
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Similarly a variant may which to include extra .udeb packages in the
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image. The list of udebs to include in an image is generated using
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tools/generate_di_list which reads one or more udeb exclude files
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from data/<distribution>/*. The syntax of these exclude files allows
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a udeb to be excluded or included based on which variants are
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enabled.
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Each line in an exclude file specifies a glob pattern, a udeb whose
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name matches the glob will _not_ be included in the image. After the
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udeb glob each line can optionally contain on or more space
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separated conditions. At least one of these conditions must be met
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in order to exclude the udeb. A condition may either be:
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- a positive `variant' condition, in which case the udeb is
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excluded when that variant is enabled
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- a negative `!variant' condition, in which case the udeb is
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excluded when that variant is not enabled.
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