* [PATCH v2] documentation: Add multiconfig initramfs configuration:
@ 2022-02-16 20:17 Alejandro Enedino Hernandez Samaniego
2022-02-17 15:51 ` [docs] " Michael Opdenacker
0 siblings, 1 reply; 2+ messages in thread
From: Alejandro Enedino Hernandez Samaniego @ 2022-02-16 20:17 UTC (permalink / raw)
To: docs; +Cc: Alejandro Enedino Hernandez Samaniego
dev-manual/common-tasks.rst: Add section to create an initramfs
image from a separate multiconfig.
ref-manual/variables.rst: Add new variable definitions for
INITRAMFS_DEPLOY_DIR_IMAGE and INITRAMFS_MULTICONFIG
Signed-off-by: Alejandro Enedino Hernandez Samaniego <alhe@linux.microsoft.com>
---
documentation/dev-manual/common-tasks.rst | 42 +++++++++++++++++++++++
documentation/ref-manual/variables.rst | 17 +++++++++
2 files changed, 59 insertions(+)
diff --git a/documentation/dev-manual/common-tasks.rst b/documentation/dev-manual/common-tasks.rst
index d35b590ee..dec44d378 100644
--- a/documentation/dev-manual/common-tasks.rst
+++ b/documentation/dev-manual/common-tasks.rst
@@ -3919,6 +3919,48 @@ Follow these steps to create an initramfs image:
:term:`INITRAMFS_IMAGE_BUNDLE`
variable described earlier.
+Bundling an Initramfs Image From a Separate Multiconfig
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There may be a case where we want to build an initramfs image which does not
+inherit the same distro policy as our main image, for example, we may want
+our main image to use ``TCLIBC="glibc"``, but to use ``TCLIBC="musl"`` in our initramfs
+image to keep a smaller footprint. However, by performing the steps mentioned
+above the initramfs image will inherit ``TCLIBC="glibc"`` without allowing us
+to override it.
+
+To achieve this, you need to perform some additional steps:
+
+1. *Create a multiconfig for your initramfs image:* You can perform the steps
+ on ":ref:`dev-manual/common-tasks:building images for multiple targets using multiple configurations`" to create a separate multiconfig.
+ For the sake of simplicity let's assume such multiconfig is called: ``initramfscfg.conf`` and
+ contains the variables::
+
+ TMPDIR="${TOPDIR}/tmp-initramfscfg"
+ TCLIBC="musl"
+
+2. *Set additional initramfs variables on your main configuration:*
+ Additionally, on your main configuration (``local.conf``) you need to set the
+ variables::
+
+ INITRAMFS_MULTICONFIG = "initramfscfg"
+ INITRAMFS_DEPLOY_DIR_IMAGE = "${TOPDIR}/tmp-initramfscfg/deploy/images/${MACHINE}"
+
+ The variables :term:`INITRAMFS_MULTICONFIG` and :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
+ are used to create a multiconfig dependency from the kernel to the :term:`INITRAMFS_IMAGE`
+ to be built coming from the ``initramfscfg`` multiconfig, and to let the
+ buildsystem know where the :term:`INITRAMFS_IMAGE` will be located.
+
+ Building a system with such configuration will build the kernel using the
+ main configuration but the ``do_bundle_initramfs`` task will grab the
+ selected :term:`INITRAMFS_IMAGE` from :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
+ instead, resulting in a musl based initramfs image bundled in the kernel
+ but a glibc based main image.
+
+ The same is applicable to avoid inheriting :term:`DISTRO_FEATURES` on :term:`INITRAMFS_IMAGE`
+ or to build a different :term:`DISTRO` for it such as ``poky-tiny``.
+
+
Building a Tiny System
----------------------
diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index d4f40b692..caa971393 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -3554,6 +3554,13 @@ system and gives an overview of their function and contents.
even if the toolchain's binaries are strippable, there are other files
needed for the build that are not strippable.
+ :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
+ Indicates the deploy directory used by ``do_bundle_initramfs`` where the
+ :term:`INITRAMFS_IMAGE` will be fetched from.
+ This variable is set by default to ``${DEPLOY_DIR_IMAGE}`` in the
+ :ref:`kernel <ref-classes-kernel>` class and it's only meant to be changed
+ when building an initramfs image from a separate multiconfig via :term:`INITRAMFS_MULTICONFIG`.
+
:term:`INITRAMFS_FSTYPES`
Defines the format for the output image of an initial RAM filesystem
(initramfs), which is used during boot. Supported formats are the
@@ -3673,6 +3680,16 @@ system and gives an overview of their function and contents.
See the :term:`MACHINE` variable for additional
information.
+ :term:`INITRAMFS_MULTICONFIG`
+ Defines the multiconfig to create a multiconfig dependency to be used by the :ref:`kernel <ref-classes-kernel>` class.
+
+ This allows the kernel to bundle an :term:`INITRAMFS_IMAGE` coming from
+ a separate multiconfig, this is meant to be used in addition to :term:`INITRAMFS_DEPLOY_DIR_IMAGE`.
+
+ For more information on how to bundle an initramfs image from a separate
+ multiconfig see the ":ref:`dev-manual/common-tasks:Bundling an Initramfs Image From a Separate Multiconfig`"
+ section in the Yocto Project Development Tasks Manual.
+
:term:`INITRAMFS_NAME`
The base name of the initial RAM filesystem image. This variable is
set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [docs] [PATCH v2] documentation: Add multiconfig initramfs configuration:
2022-02-16 20:17 [PATCH v2] documentation: Add multiconfig initramfs configuration: Alejandro Enedino Hernandez Samaniego
@ 2022-02-17 15:51 ` Michael Opdenacker
0 siblings, 0 replies; 2+ messages in thread
From: Michael Opdenacker @ 2022-02-17 15:51 UTC (permalink / raw)
To: Alejandro Hernandez Samaniego, docs
Hi Alejandro,
On 2/16/22 21:17, Alejandro Hernandez Samaniego wrote:
> dev-manual/common-tasks.rst: Add section to create an initramfs
> image from a separate multiconfig.
>
> ref-manual/variables.rst: Add new variable definitions for
> INITRAMFS_DEPLOY_DIR_IMAGE and INITRAMFS_MULTICONFIG
>
> Signed-off-by: Alejandro Enedino Hernandez Samaniego <alhe@linux.microsoft.com>
> ---
> documentation/dev-manual/common-tasks.rst | 42 +++++++++++++++++++++++
> documentation/ref-manual/variables.rst | 17 +++++++++
> 2 files changed, 59 insertions(+)
>
> diff --git a/documentation/dev-manual/common-tasks.rst b/documentation/dev-manual/common-tasks.rst
> index d35b590ee..dec44d378 100644
> --- a/documentation/dev-manual/common-tasks.rst
> +++ b/documentation/dev-manual/common-tasks.rst
> @@ -3919,6 +3919,48 @@ Follow these steps to create an initramfs image:
> :term:`INITRAMFS_IMAGE_BUNDLE`
> variable described earlier.
>
> +Bundling an Initramfs Image From a Separate Multiconfig
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +There may be a case where we want to build an initramfs image which does not
> +inherit the same distro policy as our main image, for example, we may want
> +our main image to use ``TCLIBC="glibc"``, but to use ``TCLIBC="musl"`` in our initramfs
> +image to keep a smaller footprint. However, by performing the steps mentioned
> +above the initramfs image will inherit ``TCLIBC="glibc"`` without allowing us
> +to override it.
> +
> +To achieve this, you need to perform some additional steps:
> +
> +1. *Create a multiconfig for your initramfs image:* You can perform the steps
> + on ":ref:`dev-manual/common-tasks:building images for multiple targets using multiple configurations`" to create a separate multiconfig.
> + For the sake of simplicity let's assume such multiconfig is called: ``initramfscfg.conf`` and
> + contains the variables::
> +
> + TMPDIR="${TOPDIR}/tmp-initramfscfg"
> + TCLIBC="musl"
> +
> +2. *Set additional initramfs variables on your main configuration:*
> + Additionally, on your main configuration (``local.conf``) you need to set the
> + variables::
> +
> + INITRAMFS_MULTICONFIG = "initramfscfg"
> + INITRAMFS_DEPLOY_DIR_IMAGE = "${TOPDIR}/tmp-initramfscfg/deploy/images/${MACHINE}"
> +
> + The variables :term:`INITRAMFS_MULTICONFIG` and :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
> + are used to create a multiconfig dependency from the kernel to the :term:`INITRAMFS_IMAGE`
> + to be built coming from the ``initramfscfg`` multiconfig, and to let the
> + buildsystem know where the :term:`INITRAMFS_IMAGE` will be located.
> +
> + Building a system with such configuration will build the kernel using the
> + main configuration but the ``do_bundle_initramfs`` task will grab the
> + selected :term:`INITRAMFS_IMAGE` from :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
> + instead, resulting in a musl based initramfs image bundled in the kernel
> + but a glibc based main image.
> +
> + The same is applicable to avoid inheriting :term:`DISTRO_FEATURES` on :term:`INITRAMFS_IMAGE`
> + or to build a different :term:`DISTRO` for it such as ``poky-tiny``.
> +
> +
> Building a Tiny System
> ----------------------
>
> diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
> index d4f40b692..caa971393 100644
> --- a/documentation/ref-manual/variables.rst
> +++ b/documentation/ref-manual/variables.rst
> @@ -3554,6 +3554,13 @@ system and gives an overview of their function and contents.
> even if the toolchain's binaries are strippable, there are other files
> needed for the build that are not strippable.
>
> + :term:`INITRAMFS_DEPLOY_DIR_IMAGE`
> + Indicates the deploy directory used by ``do_bundle_initramfs`` where the
> + :term:`INITRAMFS_IMAGE` will be fetched from.
> + This variable is set by default to ``${DEPLOY_DIR_IMAGE}`` in the
> + :ref:`kernel <ref-classes-kernel>` class and it's only meant to be changed
> + when building an initramfs image from a separate multiconfig via :term:`INITRAMFS_MULTICONFIG`.
> +
> :term:`INITRAMFS_FSTYPES`
> Defines the format for the output image of an initial RAM filesystem
> (initramfs), which is used during boot. Supported formats are the
> @@ -3673,6 +3680,16 @@ system and gives an overview of their function and contents.
> See the :term:`MACHINE` variable for additional
> information.
>
> + :term:`INITRAMFS_MULTICONFIG`
> + Defines the multiconfig to create a multiconfig dependency to be used by the :ref:`kernel <ref-classes-kernel>` class.
> +
> + This allows the kernel to bundle an :term:`INITRAMFS_IMAGE` coming from
> + a separate multiconfig, this is meant to be used in addition to :term:`INITRAMFS_DEPLOY_DIR_IMAGE`.
> +
> + For more information on how to bundle an initramfs image from a separate
> + multiconfig see the ":ref:`dev-manual/common-tasks:Bundling an Initramfs Image From a Separate Multiconfig`"
> + section in the Yocto Project Development Tasks Manual.
> +
> :term:`INITRAMFS_NAME`
> The base name of the initial RAM filesystem image. This variable is
> set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
Thanks for the update!
Reviewed-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
... and merged into the "master-next" branch of yocto-docs.
Cheers
Michael.
--
Michael Opdenacker, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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