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) * [Default options](#default-options) * [Installation](#installation) * [Development](#development) * [Cross](#cross) * [Architectures](#architectures) * [Portability](#portability) * [Discussion](#discussion) API --- * Runtime environment * Architecture-specific code * [Declarations](/include/kernaux/arch/) * [Functions](/include/kernaux/asm/) * [Assertions](/include/kernaux/assert.h) * [Simple](/examples/assert_simple.c) * [Guards](/examples/assert_guards.c) * Stack trace *(planned)* * Device drivers (for debugging only) * [Serial console](/include/kernaux/console.h) * [Framebuffer](/include/kernaux/framebuffer.h) *(planned)* * USB *(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) * Stivale 2 (Limine) information parser *(planned)* * [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-guard` - safely return from functions even when assertions are disabled. This option doesn't have effect if your assetion function was set and ends execution of application (kernel). However it prevents crashes and undefined behavior in other cases. You can also separately enable or disable guards: * `--(enable|disable)-guard-cond` * `--(enable|disable)-guard-null` * `--with-libc` - provides the replacement for some standard C functions. Useful in freestanding environment, where no libc is present. You can also separately include or exclude components: * `--with[out]-libc-memset` * `--with[out]-libc-strcpy` * `--with[out]-libc-strlen` ### Default options * `--with[out]-cmdline` * `--with[out]-console` * `--with[out]-elf` * `--with[out]-framebuffer` * `--with[out]-multiboot2` * `--with[out]-pfa` * `--with[out]-units` ### 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-guard make ``` You can test with `make check`. ### Cross Create configuration script with `./autogen.sh`. Let's assume that your target triplet is `i386-elf`. Configure with [cross-compiler](https://wiki.osdev.org/GCC_Cross-Compiler) in `$PATH` to make without it in `$PATH`: ``` ./configure \ --host='i386-elf' \ --enable-assert \ --enable-guard \ --with-libc \ AR="$(which i386-elf-ar)" \ CC="$(which i386-elf-gcc)" \ RANLIB="$(which i386-elf-ranlib)" \ CFLAGS='-ffreestanding -nostdlib -fno-builtin -fno-stack-protector' ``` You can see the following messages. It's [a bug](https://savannah.gnu.org/support/index.php?110393) in **autoconf**, just ignore it. ``` checking for _Bool... no checking stdarg.h usability... no checking stdarg.h presence... yes configure: WARNING: stdarg.h: present but cannot be compiled configure: WARNING: stdarg.h: check for missing prerequisite headers? configure: WARNING: stdarg.h: see the Autoconf documentation configure: WARNING: stdarg.h: section "Present But Cannot Be Compiled" configure: WARNING: stdarg.h: proceeding with the compiler's result configure: WARNING: ## ---------------------------------------------------------- ## configure: WARNING: ## Report this to https://github.com/tailix/libkernaux/issues ## configure: WARNING: ## ---------------------------------------------------------- ## checking for stdarg.h... no checking stddef.h usability... no checking stddef.h presence... yes configure: WARNING: stddef.h: present but cannot be compiled configure: WARNING: stddef.h: check for missing prerequisite headers? configure: WARNING: stddef.h: see the Autoconf documentation configure: WARNING: stddef.h: section "Present But Cannot Be Compiled" configure: WARNING: stddef.h: proceeding with the compiler's result configure: WARNING: ## ---------------------------------------------------------- ## configure: WARNING: ## Report this to https://github.com/tailix/libkernaux/issues ## configure: WARNING: ## ---------------------------------------------------------- ## checking for stddef.h... no ``` When configured with cross-compiler, library can't be build and installed with just `make && sudo make install`. Instead use the following commands: * `make libkernaux.a` * `sudo make install-exec install-data` To install into specific directory use full path: `DESTDIR="$(pwd)/dest" make install-exec install-data` instead of `DESTDIR=dest make install-exec install-data`. Check if compilation targets i386: `objdump -d src/asm/i386.o`. It should output something like this: ``` src/asm/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 ``` Architectures ------------- Architectures should be properly identified. We use the following scheme, but it may change in future: * `x86` * `i386` * `x86_64` * `riscv` * `riscv64` 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/)