Implement the selection of the picolibc source in a Kconfig
choice as they are mutually exclusive.
The following table represents the possible choices, where 'X'
means that `PICOLIBC_SUPPORTED=n` and is guarded in the parent
level as `PICOLIBC=n`, so we do not need to care.
Module Toolchain C++ | Choice
0 0 0 | X
0 0 1 | X
0 1 0 | Toolchain only
0 1 1 | Toolchain only
1 0 0 | Module only
1 0 1 | X
1 1 0 | Toolchain/Module
1 1 1 | Toolchain only
The current implementation favors `PICOLIBC_USE_TOOLCHAIN` over
`PICOLIBC_USE_MODULE` whenever possible, that preference is
maintained in this implementation as well - the TOOLCHAIN
source will be the default choice when the toolchain supports
it or when the C++ is enabled. Otherwise, fallback to MODULE.
Signed-off-by: Yong Cong Sin <ycsin@meta.com>
Since `PICOLIBC_USE_TOOLCHAIN` is available only if
`PICOLIBC` is enabled, it doesn't need to depend on the latter
again.
Signed-off-by: Yong Cong Sin <ycsin@meta.com>
The following heap-related Kconfigs shared by the picolibc &
minimal libc have been deprecated for more than 2 releases,
remove them and update the Kconfigs accordingly:
- `CONFIG_MINIMAL_LIBC_MALLOC_ARENA_SIZE`
- `CONFIG_MINIMAL_LIBC_REALLOCARRAY`
Cleanup the handling to support the deprecated malloc arena
size configuration values.
Signed-off-by: Yong Cong Sin <ycsin@meta.com>
Picolibc's 'minimal' printf mode reduces functionality and size even more
than the 'integer' mode. Use this where memory is at a premium and where
the application knows that it does not require exact printf semantics.
1.8.5 adds two more printf variants, 'long long' and 'minimal'. The 'long
long' variant is the same as the 'integer' variant but with long long
support enabled. The 'minimal' variant reduces functionality and size even
more than the 'integer' mode. Applications can use this where memory is at
a premium and where the application does not require exact printf
semantics.
With these two added variants, the SDK has enough options so that all of
the cbprintf modes can be supported with the pre-compiled bits:
1. CBPRINTF_NANO - picolibc's 'minimal' variant
2. CBPRINTF_REDUCED_INTEGRAL - picolibc's 'integer' variant
3. CBPRINTF_FULL_INTEGRAL - picolibc's 'long long' variant
4. CBPRINTF_FB_SUPPORT - picolibc's 'double' variant
This patch makes the cbprintf Kconfig values drive the default picolibc
variant, disables picolibc variants not capable of supporting the required
cbprintf level, but allows applications to select more functionality in
picolibc than cbprintf requires.
Note that this depends on the SDK including picolibc 1.8.5. Without that,
selecting the 'minimal' or 'long long' variant in Zephyr will end up with
the default variant from picolibc, which is the full version with floating
point support. When using the module things will work as specified.
Signed-off-by: Keith Packard <keithp@keithp.com>
This option in picolibc switches the assert macro between a chatty version
and one which provides no information at all. This latter mode avoids
placing the associated strings in memory.
The Zephyr option is PICOLIBC_ASSERT_VERBOSE and it is disable by default.
Signed-off-by: Keith Packard <keithp@keithp.com>
The picolibc module can be built without thread local storage support if
desired. Allow that by using 'imply' instead of 'select'. However, when
using the toolchain picolibc, we assume that TLS will be enabled wherever
supported, so make sure we match by adding a 'select' for this case.
Signed-off-by: Keith Packard <keithp@keithp.com>
...when toolchain does not have native picolibc support.
Without native support, picolibc needs to be built from
the module. Disabling the prompt means this kconfig
takes on whatever default value specified, which is
to build source from module when there is no native
support.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
The picolibc kconfigs were tied to ZEPHYR_TOOLCHAIN_VARIANT
and it only supported the Zephyr SDK, which is the only
toolchain having picolibc built-in at the moment. This
commit generalizes that to use TOOLCHAIN_HAS_PICOLIBC
cmake variable the same way as newlib: TOOLCHAIN_HAS_NEWLIB.
This provides the ability for other toolchains to declare
their support for picolibc.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
When using the Zephyr SDK toolchain, prefer the pre-built version of
picolibc over using the picolibc module. This will reduce the time it takes
to build applications.
Signed-off-by: Keith Packard <keithp@keithp.com>
Enable the common malloc implementation when using picolibc. Support
existing Picolibc configurations by respecting existing PICOLIBC_HEAP_SIZE
settings.
When PICOLIBC_HEAP_SIZE is set to a value other than -2, then
*always* set COMMON_LIBC_MALLOC_ARENA_SIZE to that value.
Signed-off-by: Keith Packard <keithp@keithp.com>
libstdc++ is supported with Picolibc only when the toolchain version of
Picolibc is use -- libstdc++ must be built using a specific Picolibc build
and libstdc++ is included with the toolchain.
Ideally, we'd allow the use of the Picolibc module whenever we weren't
using the GNU libstdc++, including when using the minimal libc++. However,
the obvious dependency settings create a loop:
config PICOLIBC
depends on PICOLIBC_SUPPORTED
config PICOLIBC_SUPPORTED
depends on !(GLIBCXX_LIBCPP && "$(ZEPHYR_TOOCHAIN_VARIANT" = "zephyr")
config GLIBCXX_LIBCPP
depends on NEWLIB_LIBC || PICOLIBC
To break this loop, we replace GLIBCXX_LIBCPP in the second block with
CPP:
config PICOLIBC_SUPPORTED
depends on !(CPP && "$(ZEPHYR_TOOCHAIN_VARIANT" = "zephyr")
This means that picolibc cannot be used with any C++ apps when using the
Zephyr SDK, even when not using the GNU libstdc++. However, Zephyr SDK 0.16
will come with an additional Kconfig file that includes:
config PICOLIBC_SUPPORTED
def_bool y
depends on "$(ZEPHYR_TOOLCHAIN_VARIANT)" = "zephyr"
This will override the Kconfig bits included in Zephyr and allow use of the
Picolibc module with C++ code, including using the minimal libc++ bits.
Signed-off-by: Keith Packard <keithp@keithp.com>
This commit updates the Picolibc configurations to remove any
unnecessary defaults and dependencies and conform to the de-facto
standard convention across the Zephyr repository.
Signed-off-by: Stephanos Ioannidis <stephanos.ioannidis@nordicsemi.no>
The picolibc heap size configuration (`CONFIG_PICOLIBC_HEAP_SIZE`) is
used to set the statically allocated malloc heap size when userspace is
enabled.
The current default heap size of 1048576 bytes (MMU) and 65536 bytes
(MPU) is too large for most platforms that Zephyr supports and may
result in the picolibc tests being filtered out due to the increased
memory footprint of the compiled image (i.e. SRAM overflow).
This commit updates the default picolibc heap size to a more reasonable
16384 bytes for MMU platforms and 1024 bytes for MPU platforms.
Signed-off-by: Stephanos Ioannidis <stephanos.ioannidis@nordicsemi.no>
Picolibc inherited its malloc arena configuration from newlib instead of
from minimal libc. This ended up making it a bit too fragile to run the
full set of zephyr tests. In particular:
* Z_MALLOC_PARTITION_EXISTS would get set when not used
* Setting an arena size depended on a bunch of other values, including
whether the system had an MMU or MPU, and whether the MPU required
power-of-two alignment or not.
This patch cleans things up so that there is a single heap size specifier,
PICOLIBC_HEAP_SIZE.
* If PICOLIBC_HEAP_SIZE is positive, this sets the size of the heap. On
MMU systems, picolibc will only use the remaining memory if that's
smaller.
* If PICOLIBC_HEAP_SIZE is zero, then there is no heap available and
malloc will always fail. This also disables Z_MALLOC_PARTITION_EXISTS.
* If PICOLIBC_HEAP_SIZE is negative, then picolibc uses all remaining
memory for the malloc heap.
The defaults are designed to allow tests to work without requiring
additional settings.
* For MMU enabled systems, the default value is 1048576. It would be nice
to have this use 'all available memory', but that's difficult to manage
as the API which returns free memory (k_mem_free_get) doesn't take into
account the amount of free virtual address space.
* For MPU enabled systems which require power-of-two aligned MPU regions,
the default value is 64kB.
* For other systems, the default value is -1, indicating that all
available memory be used for the malloc arena.
Signed-off-by: Keith Packard <keithp@keithp.com>
Picolibc is a fork of newlib designed and tested on embedded systems. It
offers a smaller memory footprint (both ROM and RAM), and native TLS
support, which uses the Zephyr TLS support.
By default, the full printf version is included in the executable, which
includes exact floating point and long long input and output. A
configuration option has been added to switch to the integer-only
version (which also omits long long support).
Here are some size comparisons using qemu-cortex-m3 and this application
(parameters passed to printf to avoid GCC optimizing it into puts):
void main(void)
{
printf("Hello World! %s %d\n", CONFIG_BOARD, 12);
}
FLASH SRAM
minimal 8696 3952
picolibc int 7600 3960
picolibc float 12304 3960
newlib-nano int 11696 4128
newlib-nano float 30516 4496
newlib 34800 6112
---
v2:
Include picolibc-tls.ld
v3:
Document usage in guides/c_library.rst and
getting_started/toolchain_other_x_compilers.rst
v4:
Lost the lib/libc/picolibc directory somehow!
v5:
Add PICOLIBC_ALIGNED_HEAP_SIZE configuration option.
Delete PICOLIBC_SEMIHOST option support code
v6:
Don't allocate static RAM for TLS values; TLS
values only need to be allocated for each thread.
v7:
Use arm coprocessor for TLS pointer storage where supported for
compatibility with the -mtp=cp15 compiler option (or when the
target cpu type selects this option)
Add a bunch of tests
Round TLS segment up to stack alignment so that overall stack
remains correctly aligned
Add aarch64 support
Rebase to upstream head
v8:
Share NEWLIB, NEWLIB_NANO and PICOLIBC library configuration
variables in a single LIBC_PARTITIONS variable instead of
having separate PICOLIBC_PART and NEWLIB_PART variables.
v9:
Update docs to reference pending sdk-ng support for picolibc
v10:
Support memory protection by creating a partition for
picolibc shared data and any pre-defined picolibc heap.
v11:
Fix formatting in arch/arm/core/aarch64/switch.S
v12:
Remove TLS support from this patch now that TLS is upstream
Require THREAD_LOCAL_STORAGE when using PICOLIBC for architectures
that support it.
v13:
Merge errno changes as they're only needed for picolibc.
Adapt cmake changes suggested by Torsten Tejlmand Rasmussen
v14:
Update to picolibc 1.7 and newer (new stdin/stdout/stderr ABI)
v15:
Respond to comments from dcpleung:
* switch kernel/errno to use CONFIG_LIBC_ERRNO instead of
CONFIG_PICOLIBC
* Add comment to test/lib/sprintf as to why the %n test
was disabled for picolibc.
v16:
Switch picolibc to a module built with Zephyr. This eliminates
toolchain dependencies and allows compiler settings for Zephyr
to also be applied to picolibc.
v17:
Provide Zephyr-specific 'abort' implementation.
Support systems with MMU
v18:
Allow use of toolchain picolibc version.
v19:
Use zephyr/ for zephyr headers
v20:
Add locking
Use explicit commit for picolibc module
v21:
Create PICOLIBC_SUPPORTED config param. Set on arc, arm, arm64,
mips and riscv architectures.
Signed-off-by: Keith Packard <keithp@keithp.com>
