| 16,8 → 16,87 |
|---|
| </mediaobject> |
| </para> |
| </section> |
| |
| <section> |
| <title>Task</title> |
| <title>Monolithic microkernel</title> |
| <para> |
| Though HelenOS was initially planned as a microkernel, we where trying to avoid several issues, connected |
| with microkernels, such as much higher overhead during memory management and hardware operations. For this reason |
| some of the subsytems, that are to be implmented as servers in classic microkernel design, where implemented |
| as a part of kernel, thus minimizing this overhead. |
| </para> |
| |
| <formalpara> |
| <title>Memory management</title> |
| <para> |
| Unlike the classic microkernel, HelenOS has all its memory management functionality in the kernel, available to the memory |
| management server via the set of syscalls. |
| </para> |
| </formalpara> |
| |
| <formalpara> |
| <title>Kernel device drivers</title> |
| <para> |
| HelenOS kernel has some of the very basic device drivers |
| <itemizedlist> |
| <listitem>ACPI</listitem> |
| <listitem>APIC</listitem> |
| <listitem>SMP configuration</listitem> |
| <listitem>System clock</listitem> |
| <listitem>Interrupt controllers</listitem> |
| <listitem>Console</listitem> |
| <listitem>VESA & frame buffer</listitem> |
| </itemizedlist> |
| |
| </para> |
| </formalpara> |
| |
| </section> |
| |
| <section> |
| <title>Kernel primitives</title> |
| <para> |
| <termdef><glossterm>Thread</glossterm> is the basic execution primitive.</termdef> |
| </para> |
| |
| <para> |
| <termdef><glossterm>Thread context</glossterm> represents state of the <emphasis>thread</emphasis>. Contains registers state, FPU state, stack(s).</termdef> |
| </para> |
| |
| <para> |
| <termdef><glossterm>Task</glossterm> </termdef> |
| </para> |
| |
| |
| <para> |
| <termdef> |
| <glossterm>Address space area</glossterm> is a mutually disjunctive range of memory with the code, stack and data. |
| </termdef> |
| </para> |
| |
| <para> |
| <termdef> |
| <glossterm>Address space</glossterm> is a aggregating entity for address space areas, connecting them to the task. |
| </termdef> |
| </para> 1 |
| </section> |
| |
| |
| |
| <section> |
| <title>IPC</title> |
| |
| <para> |
| Due to the high intertask communication traffic, IPC becomes critical subsystem for microkernels, putting high demands on the |
| speed, latency and reliability of IPC model and implementation. HelenOS IPC is designed in analogy with telephone communication. |
| Each task has an <emphasis>answerbox</emphasis> and a set of <emphasis>phones</emphasis> to call another tasks' answerboxes. Communication |
| is possible after the link establishment, and can be either <emphasis>asynchronious</emphasis> or <emphasis>synchronious</emphasis>. |
| </para> |
| |
| </section> |
| |
| |
| <section> |
| <para>Task ID - unique 64 bit number. Used for syscalls.</para> |
| <para>Contains threads</para> |
| <para>Address space is created per task</para> |
| 24,8 → 103,8 |
|---|
| <para>Memory mapping is per task</para> |
| <para>Context per thread. (Note 2 stacks on IA64).</para> |
| <para>IPC answer box associated per task</para> |
| </section> |
| <section> |
| |
| |
| <title>Memory management</title> |
| <para> |
| Zones - linked list (not many zones, so we can afford it. Can be replaced with B-tree in the future) |