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Until now, linker-tool-gcc.h was used when LLD linker was chosen. This causes linking issues because for GNU LD we use ALIGN_WITH_INPUT attribute which is not available in LLVM LLD. When using GNU LD we have to use ALIGN_WITH_INPUT to make sure that the difference between VMA and LMA remains the same between output sections that have different memory regions for VMA and LMA (RAM and FLASH). With ALIGN_WITH_INPUT it's safe to do the memcpy of sections that needs to be copied from flash to RAM in one function call: (from z_data_copy() in kernel/xip.c) ``` z_early_memcpy(&__data_region_start, &__data_region_load_start, __data_region_end - __data_region_start); ``` By default, LLVM LLD aligns both VMA and LMA to the same value, but when --omagic (-N) option is provided then only the first output section of given region has aligned LMA and the difference between VMA addresses (0 is this is the first section) is added. As a result the difference between LMA and VMA is constant for every section, so this emulates ALIGN_WITH_INPUT option present in GNU LD (required by XIP systems). The --omagic flag is defined in cmake/linker/lld/target_baremetal.cmake Example: ``` MEMORY { ROM : ORIGIN = 0x1000, LENGTH = 1K RAM : ORIGIN = 0x11000, LENGTH = 1K } SECTIONS { .text 0x1000 : { *(.text*) } >ROM .data.rel.ro : { *(.data.rel.ro) } >RAM AT>ROM .data : { *(.data*) } >RAM AT>ROM } ``` ``` echo '.globl _start; _start: nop; .byte 1;'\ '.data.rel.ro; .balign 16; .byte 0;'\ '.data; .balign 32; .byte 0;' | \ llvm-mc -filetype=obj -triple=arm - -o test.o armv7m-cros-eabi-ld.lld --sort-section=alignment -N -T script.ld \ test.o -o lld_out ``` ``` Idx Name Size VMA LMA File off Algn 0 .text 00000005 00001000 00001000 00000094 2**2 1 .data.rel.ro 00000001 00011000 00001010 000000a0 2**4 2 .data 00000001 00011020 00001030 000000c0 2**5 ``` In this example the first section has lower alignment than the following section, but with -N option the difference between VMA and LMA is the same for .data.rel.ro and .data sections. For comparison, using BFD linker with --omagic option results in the following: ``` Idx Name Size VMA LMA File off Algn 0 .text 00000005 00001000 00001000 00000094 2**2 1 .data.rel.ro 00000001 00011000 00001005 000000a0 2**4 2 .data 00000001 00011020 00001006 000000c0 2**5 ``` with ALIGN_WITH_INPUT added, GNU LD adds the difference between VMA to LMA, but doesn't align LMA of .data.rel.ro section: ``` Idx Name Size VMA LMA File off Algn 0 .text 00000005 00001000 00001000 00000074 2**2 1 .data.rel.ro 00000001 00011000 00001005 00000080 2**4 2 .data 00000001 00011020 00001025 000000a0 2**5 ``` Signed-off-by: Patryk Duda <pdk@semihalf.com> |
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.github | ||
arch | ||
boards | ||
cmake | ||
doc | ||
drivers | ||
dts | ||
include/zephyr | ||
kernel | ||
lib | ||
misc | ||
modules | ||
samples | ||
scripts | ||
share | ||
snippets | ||
soc | ||
submanifests | ||
subsys | ||
tests | ||
.checkpatch.conf | ||
.clang-format | ||
.codecov.yml | ||
.editorconfig | ||
.gitattributes | ||
.gitignore | ||
.gitlint | ||
.mailmap | ||
.yamllint | ||
CMakeLists.txt | ||
CODE_OF_CONDUCT.md | ||
CODEOWNERS | ||
CONTRIBUTING.rst | ||
Kconfig | ||
Kconfig.zephyr | ||
LICENSE | ||
MAINTAINERS.yml | ||
README.rst | ||
VERSION | ||
version.h.in | ||
west.yml | ||
zephyr-env.cmd | ||
zephyr-env.sh |
.. raw:: html <a href="https://www.zephyrproject.org"> <p align="center"> <picture> <source media="(prefers-color-scheme: dark)" srcset="doc/_static/images/logo-readme-dark.svg"> <source media="(prefers-color-scheme: light)" srcset="doc/_static/images/logo-readme-light.svg"> <img src="doc/_static/images/logo-readme-light.svg"> </picture> </p> </a> <a href="https://bestpractices.coreinfrastructure.org/projects/74"><img src="https://bestpractices.coreinfrastructure.org/projects/74/badge"></a> <a href="https://github.com/zephyrproject-rtos/zephyr/actions/workflows/twister.yaml?query=branch%3Amain"> <img src="https://github.com/zephyrproject-rtos/zephyr/actions/workflows/twister.yaml/badge.svg?event=push"></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-A, Cortex-R, Cortex-M), Intel x86, ARC, Nios II, Tensilica Xtensa, and RISC-V, SPARC, MIPS, 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 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/develop/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/develop/getting_started/index.html#asking-for-help