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linux/Documentation/powerpc/bootwrapper.rst

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docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
========================
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
The PowerPC boot wrapper
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
========================
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
Copyright (C) Secret Lab Technologies Ltd.
PowerPC image targets compresses and wraps the kernel image (vmlinux) with
a boot wrapper to make it usable by the system firmware. There is no
standard PowerPC firmware interface, so the boot wrapper is designed to
be adaptable for each kind of image that needs to be built.
The boot wrapper can be found in the arch/powerpc/boot/ directory. The
Makefile in that directory has targets for all the available image types.
The different image types are used to support all of the various firmware
interfaces found on PowerPC platforms. OpenFirmware is the most commonly
used firmware type on general purpose PowerPC systems from Apple, IBM and
others. U-Boot is typically found on embedded PowerPC hardware, but there
are a handful of other firmware implementations which are also popular. Each
firmware interface requires a different image format.
The boot wrapper is built from the makefile in arch/powerpc/boot/Makefile and
it uses the wrapper script (arch/powerpc/boot/wrapper) to generate target
image. The details of the build system is discussed in the next section.
Currently, the following image format targets exist:
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
==================== ========================================================
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
cuImage.%: Backwards compatible uImage for older version of
U-Boot (for versions that don't understand the device
tree). This image embeds a device tree blob inside
the image. The boot wrapper, kernel and device tree
are all embedded inside the U-Boot uImage file format
with boot wrapper code that extracts data from the old
bd_info structure and loads the data into the device
tree before jumping into the kernel.
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
Because of the series of #ifdefs found in the
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
bd_info structure used in the old U-Boot interfaces,
cuImages are platform specific. Each specific
U-Boot platform has a different platform init file
which populates the embedded device tree with data
from the platform specific bd_info file. The platform
specific cuImage platform init code can be found in
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
`arch/powerpc/boot/cuboot.*.c`. Selection of the correct
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
cuImage init code for a specific board can be found in
the wrapper structure.
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
dtbImage.%: Similar to zImage, except device tree blob is embedded
inside the image instead of provided by firmware. The
output image file can be either an elf file or a flat
binary depending on the platform.
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
dtbImages are used on systems which do not have an
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
interface for passing a device tree directly.
dtbImages are similar to simpleImages except that
dtbImages have platform specific code for extracting
data from the board firmware, but simpleImages do not
talk to the firmware at all.
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
PlayStation 3 support uses dtbImage. So do Embedded
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
Planet boards using the PlanetCore firmware. Board
specific initialization code is typically found in a
file named arch/powerpc/boot/<platform>.c; but this
can be overridden by the wrapper script.
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
simpleImage.%: Firmware independent compressed image that does not
depend on any particular firmware interface and embeds
a device tree blob. This image is a flat binary that
can be loaded to any location in RAM and jumped to.
Firmware cannot pass any configuration data to the
kernel with this image type and it depends entirely on
the embedded device tree for all information.
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
treeImage.%; Image format for used with OpenBIOS firmware found
on some ppc4xx hardware. This image embeds a device
tree blob inside the image.
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
uImage: Native image format used by U-Boot. The uImage target
does not add any boot code. It just wraps a compressed
vmlinux in the uImage data structure. This image
requires a version of U-Boot that is able to pass
a device tree to the kernel at boot. If using an older
version of U-Boot, then you need to use a cuImage
instead.
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
zImage.%: Image format which does not embed a device tree.
Used by OpenFirmware and other firmware interfaces
which are able to supply a device tree. This image
expects firmware to provide the device tree at boot.
Typically, if you have general purpose PowerPC
hardware then you want this image format.
docs: powerpc: convert docs to ReST and rename to *.rst Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
2019-04-10 14:32:42 +03:00
==================== ========================================================
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
Image types which embed a device tree blob (simpleImage, dtbImage, treeImage,
and cuImage) all generate the device tree blob from a file in the
arch/powerpc/boot/dts/ directory. The Makefile selects the correct device
tree source based on the name of the target. Therefore, if the kernel is
powerpc: Remove Xilinx PPC405/PPC440 support The latest Xilinx design tools called ISE and EDK has been released in October 2013. New tool doesn't support any PPC405/PPC440 new designs. These platforms are no longer supported and tested. PowerPC 405/440 port is orphan from 2013 by commit cdeb89943bfc ("MAINTAINERS: Fix incorrect status tag") and commit 19624236cce1 ("MAINTAINERS: Update Grant's email address and maintainership") that's why it is time to remove the support fot these platforms. Signed-off-by: Michal Simek <michal.simek@xilinx.com> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/8c593895e2cb57d232d85ce4d8c3a1aa7f0869cc.1590079968.git.christophe.leroy@csgroup.eu
2020-05-21 19:55:52 +03:00
built with 'make treeImage.walnut', then the build system will use
arch/powerpc/boot/dts/walnut.dts to build treeImage.walnut.
powerpc/bootwrapper: Add documentation of boot wrapper targets There have been many questions on and off the mailing list about how exactly the bootwrapper is used for embedded targets. Add some documentation and help text to try and clarify the system. Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2008-06-26 00:14:36 +04:00
Two special targets called 'zImage' and 'zImage.initrd' also exist. These
targets build all the default images as selected by the kernel configuration.
Default images are selected by the boot wrapper Makefile
(arch/powerpc/boot/Makefile) by adding targets to the $image-y variable. Look
at the Makefile to see which default image targets are available.
How it is built
---------------
arch/powerpc is designed to support multiplatform kernels, which means
that a single vmlinux image can be booted on many different target boards.
It also means that the boot wrapper must be able to wrap for many kinds of
images on a single build. The design decision was made to not use any
conditional compilation code (#ifdef, etc) in the boot wrapper source code.
All of the boot wrapper pieces are buildable at any time regardless of the
kernel configuration. Building all the wrapper bits on every kernel build
also ensures that obscure parts of the wrapper are at the very least compile
tested in a large variety of environments.
The wrapper is adapted for different image types at link time by linking in
just the wrapper bits that are appropriate for the image type. The 'wrapper
script' (found in arch/powerpc/boot/wrapper) is called by the Makefile and
is responsible for selecting the correct wrapper bits for the image type.
The arguments are well documented in the script's comment block, so they
are not repeated here. However, it is worth mentioning that the script
uses the -p (platform) argument as the main method of deciding which wrapper
bits to compile in. Look for the large 'case "$platform" in' block in the
middle of the script. This is also the place where platform specific fixups
can be selected by changing the link order.
In particular, care should be taken when working with cuImages. cuImage
wrapper bits are very board specific and care should be taken to make sure
the target you are trying to build is supported by the wrapper bits.
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