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<chapter id="architecture"><?dbhtml filename="arch.html"?>

	<title>Architecture overview</title>

	<section>

		<title>Task</title>

		<para>Task ID - unique 64 bit number. Used for syscalls.</para>

		<para>Contains threads</para>

		<para>Address space is created per task</para>

		<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)

		Number of zones depends on HW tables. Describe zone allocation/deallocation algoritm

		</para>

		<para>Page tables. 4 level hierarchical and hash directly supported. B+ Tree can be implemented.</para>

		<para>For paging there is an abstract layer</para>

		<para>TLB shootdown implementation (update TLB upon mapping update/remove). 

		TLB shootdown ASID/ASID:PAGE/ALL.

		TLB shootdown requests can come in asynchroniously

		so there is a cache of TLB shootdown requests. Upon cache overflow TLB shootdown ALL is executed</para>

		<para>

			Address spaces. Address space area (B+ tree). Only for uspace. Set of syscalls (shrink/extend etc).

			Special address space area type - device - prohibits shrink/extend syscalls to call on it.

			Address space has link to mapping tables (hierarchical - per Address space, hash - global tables).

		</para>

	</section>

</chapter>