CHANGELOG-0.2.0.md

Firedrake 0.2.0:512 (Sunrise Jade)

Overview

Firedrake 0.2.0 changes a lot of things under the hood, mainly related to the handling of memory and the execution of processes and the handling of their syscalls. Unlike previous versions, Firedrake now gives each process its own 4gb address space and handles interrupts via a trampoline area in the memory space which is responsible for loading the kernels address space and call the interrupt handler there, this is the only part of the kernel which is mapped into a process' address space, otherwise the whole 4gb are reserved for the process.

The kernel can also load ELF binaries from multiboot modules now, as long as they are selfcontained executables. Dynamic libraries are not resolved and no relocation is done by the kernel or a dynamic linker. Spinlocks are also reintroduced, although not completely covering all possible areas (eg. the memory related stuff is not yet threadsafe!)

Changes

Kernel

• Added dylink which is able to load ELF binaries
• Added the possibility for the kernel to create processes from ELF binaries
• Added a completly rewritten interrupt handler
• Added kunit which is able to run in kernel unit-tests
• Added config.h which can be used to configure various stuff (eg. the exectuion of unit-tests, force to not-inline some functions for better stacktraces etc)
• Added stacktraces for the kernel which enables the kernel to dump the callstack in case of errors
• Added various stuff to the kernels libc subset, most notably setjmp/longjmp, strcmp, strstr, strcpy, strncmp and strpbrk
• Added a high level memory allocator for the kernel which allows for smaller allocations than the previous kalloc() which always allocated at least one whole page
• Added new logging macros, dbg, err, warn and info which call syslog() with LOG_DEBUG, LOG_ERROR, LOG_WARNING, and LOG_INFO respectively
• Changed vsnprintf() now accepts flag and width arguments in the format string
• Changed the order of boot module initialization, previously the interrupt handler was loaded before the memory management system, this is now changed
• Changed the colors for LOG_ERROR and LOG_WARNING are switched now
• Changed structs now use the _s suffix and only typedeffed stuff use the _t suffix
• Changed vm_init() now also maps the multiboot info, except of the memory mapping information!
• Changed vm_offset_t is now called vm_address_t
• Changed vm_getPhysicalAddress() is now named vm_resolveVirtualAddress()
• Changed syscalls now return an errno value
• Fixed various virtual memory related functions which crashed because they accessed unmapped memory
• Fixed a bug in atof() which ignored numbers after the decimal seperator.
• Fixed the multiboot info and the multiboot modules are now marked as used by the physical memory manager, so they are no longer overwritten at runtime.
• Removed ceil, ceilf, fabs and dabs from math.h (the goal was to remove all floating point code from the kernel).

Libraries

• Note this is the first release of Firedrake which includes libraries. Currently only static libraries are supported because of the lack of an dynamic linker
• Added libcrt, usually this is just an .o file, however currently its provided as an .a static library, it only implements _start() which then calls the main() function of the actual program
• Added libtest, static test library which just implements C routines for most syscalls and also implements some other stuff like errno

Programs

• Note this is the first release of Firedrake which includes programs.
• Added hellostatic, a simple program which puts a message on the screen, creates a secondary thread and then joins the thread.

Notes

• Firedrake now perfectly compiles and links using LLVM/Clang 3.1, it also uses -O2 optimization and thus is much faster and lighter than previous versions.
• This release has been tested on Qemu and VMWare Fusion 4.1.3

Screenshots