Zephyr is a bare metal build where standard libs are disabled.
This means that c and runtime libraries must manually be linked in.
This has generally been handled by using CMake's link libraries handling
but the issue with that is both de-duplication but also library link
order.
Standard libraries must be linked at last location to ensure symbols
are always available, however this is not optimal with
target_link_libraries() because this would ultimately require every
library to know the c library to link with, which is not desired.
Therefore, setup standard C and runtime library linking in linker
CMake files for toolchains where this is required.
This commit expands the principle introduced with toolchain abstraction,
see PR#24851.
This means that a toolchain implementation may specify standard C,
runtime, C++, etc libraries, as well as their link order.
Because a property approach is used, then Zephyr modules, such as the
Picolibc module can adjust such properties.
An optional `zephyr_linker_finalize()` macro is called at the end of
Zephyr's CMakeList process and can be used by the toolchain
implementation to define the final linker invocation.
This aligns the linker handling flow to the principle introduced in
PR#24851 and improves the flexibility and robustness of Zephyr build
system.
Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
This commit reverts a breaking change in CMAKE_SYSTEM_NAME introduced by
"Zephyr" back to "Generic") and removes the file
`cmake/modules/Platform/Zephyr`.
Both changes in the aforementioned PR were only introduced to ultimately
modify the value of the global CMake property TARGET_SUPPORTS_SHARED_LIBS
for the special case of building for Xtensa with LLEXT.
The modification of CMAKE_SYSTEM_NAME is considered a breaking change
because it has the potential to alter the build of any non-trivial project
that previously checked for the "Generic" system identifier as
corresponding to Zephyr - for example by doing
`if (CMAKE_SYSTEM_NAME STREQUAL "Generic")`. Such builds may now break in
many ways including silently when there is no `else()` clause with a
`message()` to alert the user that a whole configuration block had been
skipped.
In essence, that CMAKE_SYSTEM_NAME modification was only introduced in
order to have CMake to load `cmake/modules/Platform/Zephyr.cmake` which in
turn adjusted the value of TARGET_SUPPORTS_SHARED_LIBS.
But the use of a CMake platform file like this is ineffective for
non-trivial projects where one or more top level CMake `project()` calls
may happen before the first call to `find_package(Zephyr)` because in such
cases CMAKE_MODULE_PATH will not have been modified yet to contain the
path to <Zephyr_ROOT>/cmake/modules and thus no platform file will be
include by CMake.
This patch moves the conditional override of TARGET_SUPPORTS_SHARED_LIBS
needed by some archs (e.g. Xtensa) into the `kernel.cmake` module which
is known to be the first call to `project()` that enables any language and
thus the one that must come before any artifact target can be defined.
Note commit 64e7d85 added a Kconfig to specify the object type of llext
being built, so it's not tied to the arch anymore but to the
CONFIG_LLEXT_TYPE_ELF_SHAREDLIB option.
Signed-off-by: Nicolas Lebedenco <nicolas@lebedenco.net>
When CONFIG_LLEXT is enabled, the Zephyr platform needs to enable dynamic
library support. This is done by setting the `TARGET_SUPPORTS_SHARED_LIBS`
property to `TRUE` in the global property scope.
Signed-off-by: Luca Burelli <l.burelli@arduino.cc>
Fixes: #45270
Zephyr Kconfig defines the settings BIG_ENDIAN.
Propagate this setting to the corresponding CMAKE_C_BYTE_ORDER and
CMAKE_CXX_BYTE_ORDER variables.
This also ensures that the CMake function 'is_big_endian()' reports the
correct endianess.
Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
Follow-up: #41301
This commit is a rework and cleanup of the target toolchain handling in
Zephyr CMake build system.
Instead of directly loading code a CMake modules for target toolchain
lookup, the target toolchain now follows the CMake `find_package()`
pattern for finding the target toolchain.
This makes it more clear which modules are responsible for finding tools
and which modules provides build integration / features.
The following tools can now be found using `find_package()`:
- Target toolchain: find_package(TargetTools)
Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
2022-09-01 15:59:43 +02:00
Renamed from cmake/modules/target_toolchain.cmake (Browse further)
