libkernaux ========== [![Test](https://github.com/tailix/libkernaux/actions/workflows/test.yml/badge.svg)](https://github.com/tailix/libkernaux/actions/workflows/test.yml) Auxiliary library for kernel development. Table of contents ----------------- * [Overview](#libkernaux) * [Table of contents](#table-of-contents) * [API](#api) * [Tips](#tips) * [Non-default options](#non-default-options) * [Installation](#installation) * [Development](#development) * [Cross](#cross) * [Portability](#portability) * [Discussion](#discussion) * [Summary](#summary) * [Pure code size](#pure-code-size) * [Used header files](#used-header-files) API --- * Runtime environment * [Assertions](/include/kernaux/assert.h) * [Simple](/examples/assert_simple.c) * [With return](/example/assert_return.c) * [Architecture-specific helpers](/include/kernaux/arch/) * Device drivers (for debugging only) * [Serial console](/include/kernaux/console.h) * Framebuffer *(planned)* * Algorithms * [Simple command line parser](/include/kernaux/cmdline.h) * [Example](/examples/cmdline.c) * [Page Frame Allocator](/include/kernaux/pfa.h) * [Example](/examples/pfa.c) * Data formats * [Multiboot 2 (GRUB 2) information parser](/include/kernaux/multiboot2.h) * [ELF utils](/include/kernaux/elf.h) *(work in progress)* * Utilities * [Measurement units utils](/include/kernaux/units.h) *(work in progress)* * [To human](/examples/units_human.c) * Usual functions * [libc replacement](/include/kernaux/libc.h) * `memset` * `strcpy` * `strlen` * [itoa replacement](/include/kernaux/itoa.h) *(work in progress)* * [printf replacement](/include/kernaux/printf.h) *(work in progress)* * [printf](/examples/printf.c) * [printf_va](/examples/printf_va.c) Tips ---- ### Non-default options Because this library has no external dependencies, we use **autoconf** features to control behavior of the library, and packages to choose it's components. Here are some non-default options: * `--enable-assert` - use value of extern variable `kernaux_assert_cb` as a callback function for internal assertions. You still can use assertions in your own application (kernel) even if this option was not enabled. * `--enable-null-guard` - safely return from functions which require non-null pointers as arguments. NULL-guard works with assertions, so this option doesn't have effect if your assetion function was set and ends execution of application (kernel). However it prevents crashes because of NULL pointer dereference in other cases. * `--with-libc` - provides the replacement for some standard C functions. Useful in freestanding environment, where no libc is present. ### Installation ``` ./autogen.sh ./configure make sudo make install ``` This is just a usual library. You can use most of it's APIs in hosted environment. ### Development ``` ./autogen.sh ./configure --enable-assert --enable-null-guard make ``` You can test with `make check`. ### Cross The library depends on `stdint.h` header. According to the standards it must be present in freestanding environment. However when you build GCC cross-compiler using [instructions from OSDev Wiki](https://wiki.osdev.org/GCC_Cross-Compiler) the header is missing. To fix this issue you may add `use_gcc_stdint=provide` to the end of `gcc/config.gcc` in your GCC source code extracted from tarball: ``` echo 'use_gcc_stdint=provide' >> gcc-11.2.0/gcc/config.gcc ``` --- Create configuration script with `./autogen.sh`. 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' \ --with-libc \ AR="$(which i386-elf-ar)" \ CC="$(which i386-elf-gcc)" \ RANLIB="$(which i386-elf-ranlib)" \ CFLAGS='-ffreestanding -nostdlib -fno-builtin -fno-stack-protector' ``` You can see the following messages. It's [a bug](https://savannah.gnu.org/support/index.php?110393) in **autoconf**, just ignore it. ``` checking for _Bool... no checking stdarg.h usability... no checking stdarg.h presence... yes configure: WARNING: stdarg.h: present but cannot be compiled configure: WARNING: stdarg.h: check for missing prerequisite headers? configure: WARNING: stdarg.h: see the Autoconf documentation configure: WARNING: stdarg.h: section "Present But Cannot Be Compiled" configure: WARNING: stdarg.h: proceeding with the compiler's result configure: WARNING: ## ---------------------------------------------------------- ## configure: WARNING: ## Report this to https://github.com/tailix/libkernaux/issues ## configure: WARNING: ## ---------------------------------------------------------- ## checking for stdarg.h... no checking stddef.h usability... no checking stddef.h presence... yes configure: WARNING: stddef.h: present but cannot be compiled configure: WARNING: stddef.h: check for missing prerequisite headers? configure: WARNING: stddef.h: see the Autoconf documentation configure: WARNING: stddef.h: section "Present But Cannot Be Compiled" configure: WARNING: stddef.h: proceeding with the compiler's result configure: WARNING: ## ---------------------------------------------------------- ## configure: WARNING: ## Report this to https://github.com/tailix/libkernaux/issues ## configure: WARNING: ## ---------------------------------------------------------- ## checking for stddef.h... no ``` To install into specific directory use full path: `DESTDIR="$(pwd)/dest" make install` instead of `DESTDIR=dest make install`. When configured with cross-compiler, library can't be build and installed with just `make && sudo make install`. Instead use the following commands: * `make libkernaux.a` * `sudo make install-exec` * `sudo make install-data` Check if compilation targets i386: `objdump -d src/arch/i386.o`. It should output something like this: ``` src/arch/i386.o: file format elf32-i386 Disassembly of section .text: 00000000 : 0: fa cli 1: f4 hlt 2: eb fc jmp 0 00000004 : 4: 0f 20 c0 mov %cr0,%eax 7: c3 ret 00000008 : 8: 0f 20 e0 mov %cr4,%eax b: c3 ret 0000000c : c: 8b 44 24 04 mov 0x4(%esp),%eax 10: 0f 22 c0 mov %eax,%cr0 13: c3 ret 00000014 : 14: 8b 44 24 04 mov 0x4(%esp),%eax 18: 0f 22 d8 mov %eax,%cr3 1b: c3 ret 0000001c : 1c: 8b 44 24 04 mov 0x4(%esp),%eax 20: 0f 22 e0 mov %eax,%cr4 23: c3 ret ``` Portability ----------- Except GNU/Linux, the library is periodically successfully built (starting with `./autogen.sh`) and tested with **autoconf**, **automake**, **binutils** and **gcc**/**clang** (depending on what is present) on the following operating systems: * FreeBSD 13.0 * Minix 3.3.0 * NetBSD 9.2 * OpenBSD 7.0 Discussion ---------- * [Topic on OSDev.org forum](https://forum.osdev.org/viewtopic.php?f=1&t=37958) * [Thread on r/osdev](https://www.reddit.com/r/osdev/comments/k3ueeu/libkernaux_auxiliary_library_for_kernel/) Summary ------- This information is updated from time to time. ### Pure code size `cloc --vcs=git include/ src/` ``` ------------------------------------------------------------------------------- Language files blank comment code ------------------------------------------------------------------------------- C 12 236 19 1548 C/C++ Header 14 179 64 597 Assembly 2 7 6 28 make 1 0 0 13 ------------------------------------------------------------------------------- SUM: 29 422 89 2186 ------------------------------------------------------------------------------- ``` ### Used header files `git grep '#include <' -- include/ src/ | grep -v '#include