libclayer/README.md

libkernaux

Auxiliary library for kernel development.

Topic on OSDev.org forum.

Table of contents

• Overview
• Table of contents
• API
  • Headers
  • Definitions
  • Global variables
• Configuration
  • Non-default options
  • Default options
• Tips
  • Installation
  • Development
  • Cross

API

Headers

We use semantic versioning for stable APIs. Stable APIs may only change when major version number is increased (or minor while major is zero). Work-in-progress APIs can change at any time.

• Basic features
  • Macros (non-breaking since 0.6.0)
  • Stack trace (planned)
• libc replacement (work in progress)
  • ctype.h
  • errno.h
  • inttypes.h
  • setjmp.h
  • stdlib.h
  • string.h
  • sys/types.h

Definitions

#define the following C preprocessor macros before including <kernaux.h> and <kernaux/*.h> files. They have effect on your code, not the library code.

• KERNAUX_ACCESS_PRIVATE - disable access modifier "private". Don't do this!
• KERNAUX_ACCESS_PROTECTED - disable access modifier "protected". Only do this in a file where you implement an inherited type.
• KERNAUX_BITFIELDS - enable bitfields in packed structs. It doesn't follow the C standard and may be incompatible with some compilers.

Configuration

Because this library has no external dependencies, we use autoconf features to control behavior of the library, and packages to choose it's components. Configuration options also follow the semantic versioning scheme and are split into stable and work-in-progress ones. Here we cover only stable options.

Non-default options

Features

• --enable-checks - enable usual tests
• --enable-checks-all - enable all checks
• --enable-checks-cppcheck - enable cppcheck Jinja2
• --enable-pkg-config[=PATH] - install pkg-config files [PATH='${libdir}/pkgconfig']

Packages

• --with-libc - provides the replacement for some standard C functions. Useful in freestanding environment, where no libc is present.

Default options

Features

• --(enable|disable)-float - floating-point arithmetic
• --(enable|disable)-werror - fail on warning (CFLAGS+='-Werror')

Tips

Installation

./autogen.sh # if present
./configure
make
sudo make install
sudo ldconfig # on GNU/Linux

This is just a usual library. You can use most of it's APIs in hosted environment.

Development

./autogen.sh # if present
./configure --enable-checks # or --enable-checks-all, but see prerequisites
make

You can test with make check.

See also

• GitHub Actions for GNU/Linux build environment
• Cirrus CI for FreeBSD build environment
• sourcehut CI for OpenBSD build environment

Cross

Create configuration script with ./autogen.sh (if present).

Let's assume that your target triplet is i386-elf. Configure with cross-compiler in $PATH to make without it in $PATH:

./configure \
  --host='i386-elf' \
  --disable-shared \
  --enable-freestanding \
  --with-libc \
  CC="$(which i386-elf-gcc)"

The variables include AR, AS, CC, CCAS, LD, NM, OBJDUMP, RANLIB, STRIP. See the generated config.log for more information.

To install into specific directory use full path: DESTDIR="$(pwd)/dest" make install instead of DESTDIR=dest make install.