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Martí Bolívar a627666e06 device: add fudge factor for handle padding 
When CONFIG_USERSPACE is enabled, the ELF file from linker pass 1 is
used to create a hash table that identifies kernel objects by address.
We therefore can't allow the size of any object in the pass 2 ELF to
change in a way that would change those addresses, or we would create
a garbage hash table.

Simultaneously (and regardless of CONFIG_USERSPACE's value),
gen_handles.py must transform arrays of handles from their pass 1
values to their pass 2 values; see the file's docstring for more
details on that transformation.

The way this works is that gen_handles.py just pads out each pass 2
array so its length is the same as its pass 1 value. The padding value
is a repeated run of DEVICE_HANDLE_ENDS values. This value is the
terminator which we look for at runtime in places like
device_required_handles_get(), so there must be at least one, and we
error out in gen_handles.py if there's no room in the pass 2 array for
at least one such value. (If there is extra room, we just keep
inserting extra DEVICE_HANDLE_ENDS values to pad the array to its
original length.)

However, it is possible that a device has more direct dependencies in
the pass 2 handles array than its corresponding devicetree node had in
the pass 1 array. When this happens, users have no recourse, so that's
a potential showstopper.

To work around this possibility for now, add a new config option,
CONFIG_DEVICE_HANDLE_PADDING, whose value defaults to 0.

When nonzero, it is a count of padding handles that are inserted into
each device handles array. When gen_handles.py errors out due to lack
of room, its error message now tells the user how much to increase
CONFIG_DEVICE_HANDLE_PADDING by to work around the problem.

It looks like a real fix for this is to allocate kernel objects whose
addresses are required for hash tables in CONFIG_USERSPACE=y
configurations *before* the handle arrays. The handle arrays could
then be resized as needed in pass 2, which saves ROM by avoiding
unnecessary padding, and would avoid the need for
CONFIG_DEVICE_HANDLE_PADDING altogether.

However, this 'real fix' is not available and we are facing a deadline
to get a temporary solution in for Zephyr v2.7.0, so this is a good
enough workaround for now.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>
2021-09-30 21:37:59 -04:00
.buildkite ci: Bump to use SDK 0.13.1 2021-09-21 13:03:02 -04:00
.github templates: fix label for feature request 2021-09-29 14:13:48 -04:00
arch xtensa: fix implicit declaration of _xtensa_handle_one_int* 2021-09-28 20:33:56 -04:00
boards soc: riscv: esp32c3: update west version 2021-09-30 06:39:55 -04:00
cmake toolchain: esp32: define target toolchain 2021-09-28 20:06:25 -04:00
doc doc: Add deadline scheduling information 2021-09-30 17:01:09 -04:00
drivers Revert "drivers: spi: stm32 can support TI mode for the SPI frame format" 2021-09-30 16:04:37 -04:00
dts Revert "dts: stm32 spi can configure the frame-format" 2021-09-30 16:04:37 -04:00
include device: add fudge factor for handle padding 2021-09-30 21:37:59 -04:00
kernel device: add fudge factor for handle padding 2021-09-30 21:37:59 -04:00
lib json: Changes enum name of square brackets from list to array 2021-09-28 19:52:10 -04:00
misc toolchain: add GEN_ABSOLUTE_SYM_KCONFIG() 2021-02-02 09:23:45 -05:00
modules modules: mbedtls: Allow custom mbedtls implementation 2021-09-29 15:32:40 -04:00
samples samples: sensor: fxos8700: add mimxrt1024_evk board configuration 2021-09-29 10:07:41 -04:00
scripts device: add fudge factor for handle padding 2021-09-30 21:37:59 -04:00
share cmake: check zephyr version if specified and ZEPHYR_BASE is set 2021-05-25 16:48:35 -05:00
soc soc: riscv: esp32c3: update west version 2021-09-30 06:39:55 -04:00
subsys pm: stop handling devices on PM_STATE_RUNTIME_IDLE 2021-09-30 16:05:59 -04:00
tests Revert "tests: devicetree: test supported devices API" 2021-09-30 21:37:59 -04:00
.checkpatch.conf checkpatch: ignore linux specific ENOSYS warning 2021-03-30 10:50:14 -05:00
.clang-format clang-format: Change lines length limit from 80 to 100 2021-05-06 08:13:32 -05:00
.codecov.yml
.editorconfig
.gitattributes
.gitignore gitignore: add common Python venv directories 2021-04-20 11:30:40 -05:00
.gitlint
.mailmap mailmap: update mailmap file with some stray emails 2021-06-17 14:15:41 -04:00
.uncrustify.cfg
CMakeLists.txt cmake: compiler: Add framework for disabling C++ standard includes 2021-09-21 11:39:18 -04:00
CODE_OF_CONDUCT.md
CODEOWNERS esp32: drivers: clock_control: add ownership 2021-09-27 22:02:08 -04:00
CONTRIBUTING.rst
Kconfig
Kconfig.zephyr kconfig: add names to some choices 2021-09-28 19:56:32 -04:00
LICENSE
MAINTAINERS.yml MAINTAINERS: Add IPC maintainers 2021-09-27 21:47:33 -04:00
README.rst doc: Document the switch from Slack to Discord 2021-09-03 08:11:15 -04:00
VERSION VERSION: bump main branch to 2.7.99 2021-09-30 06:36:53 -04:00
version.h.in
west.yml soc: riscv: esp32c3: update west version 2021-09-30 06:39:55 -04:00
zephyr-env.cmd
zephyr-env.sh

README.rst 

.. raw:: html

   <a href="https://www.zephyrproject.org">
     <p align="center">
       <img src="doc/_static/images/logo-readme.png">
     </p>
   </a>

   <a href="https://bestpractices.coreinfrastructure.org/projects/74"><img
   src="https://bestpractices.coreinfrastructure.org/projects/74/badge"></a>
   <a href="https://buildkite.com/zephyr/zephyr">
   <img
   src="https://badge.buildkite.com/f5bd0dc88306cee17c9b38e78d11bb74a6291e3f40e7d13f31.svg?branch=main"></a>


The Zephyr Project is a scalable real-time operating system (RTOS) supporting
multiple hardware architectures, optimized for resource constrained devices,
and built with security in mind.

The Zephyr OS is based on a small-footprint kernel designed for use on
resource-constrained systems: from simple embedded environmental sensors and
LED wearables to sophisticated smart watches and IoT wireless gateways.

The Zephyr kernel supports multiple architectures, including ARM Cortex-M,
Intel x86, ARC, Nios II, Tensilica Xtensa, and RISC-V, and a large number of
`supported boards`_.

.. below included in doc/introduction/introduction.rst


Getting Started
***************

Welcome to Zephyr! See the `Introduction to Zephyr`_ for a high-level overview,
and the documentation's `Getting Started Guide`_ to start developing.

.. start_include_here

Community Support
*****************

Community support is provided via mailing lists and Discord; see the Resources
below for details.

.. _project-resources:

Resources
*********

Here's a quick summary of resources to help you find your way around:

* **Help**: `Asking for Help Tips`_
* **Documentation**: http://docs.zephyrproject.org (`Getting Started Guide`_)
* **Source Code**: https://github.com/zephyrproject-rtos/zephyr is the main
  repository; https://elixir.bootlin.com/zephyr/latest/source contains a
  searchable index
* **Releases**: https://github.com/zephyrproject-rtos/zephyr/releases
* **Samples and example code**: see `Sample and Demo Code Examples`_
* **Mailing Lists**: users@lists.zephyrproject.org and
  devel@lists.zephyrproject.org are the main user and developer mailing lists,
  respectively. You can join the developer's list and search its archives at
  `Zephyr Development mailing list`_. The other `Zephyr mailing list
  subgroups`_ have their own archives and sign-up pages.
* **Nightly CI Build Status**: https://lists.zephyrproject.org/g/builds
  The builds@lists.zephyrproject.org mailing list archives the CI
  (buildkite) nightly build results.
* **Chat**: Real-time chat happens in Zephyr's Discord Server. Use
  this `Discord Invite`_ to register.
* **Contributing**: see the `Contribution Guide`_
* **Wiki**: `Zephyr GitHub wiki`_
* **Issues**: https://github.com/zephyrproject-rtos/zephyr/issues
* **Security Issues**: Email vulnerabilities@zephyrproject.org to report
  security issues; also see our `Security`_ documentation. Security issues are
  tracked separately at https://zephyrprojectsec.atlassian.net.
* **Zephyr Project Website**: https://zephyrproject.org

.. _Discord Invite: https://chat.zephyrproject.org
.. _supported boards: http://docs.zephyrproject.org/latest/boards/index.html
.. _Zephyr Documentation: http://docs.zephyrproject.org
.. _Introduction to Zephyr: http://docs.zephyrproject.org/latest/introduction/index.html
.. _Getting Started Guide: http://docs.zephyrproject.org/latest/getting_started/index.html
.. _Contribution Guide: http://docs.zephyrproject.org/latest/contribute/index.html
.. _Zephyr GitHub wiki: https://github.com/zephyrproject-rtos/zephyr/wiki
.. _Zephyr Development mailing list: https://lists.zephyrproject.org/g/devel
.. _Zephyr mailing list subgroups: https://lists.zephyrproject.org/g/main/subgroups
.. _Sample and Demo Code Examples: http://docs.zephyrproject.org/latest/samples/index.html
.. _Security: http://docs.zephyrproject.org/latest/security/index.html
.. _Asking for Help Tips: https://docs.zephyrproject.org/latest/getting_started/index.html#asking-for-help