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  1. <?xml version="1.0" encoding="UTF-8"?>
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  3. <chapter id="architecture"><?dbhtml filename="arch.html"?>
  4.     <title>Architecture overview</title>
  5.     <section>
  6.         <title>Scheme</title>
  7.         <para>
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  17.         </para>
  18.     </section>
  19.     <section>
  20.         <title>Task</title>
  21.         <para>Task ID - unique 64 bit number. Used for syscalls.</para>
  22.         <para>Contains threads</para>
  23.         <para>Address space is created per task</para>
  24.         <para>Memory mapping is per task</para>
  25.         <para>Context per thread. (Note 2 stacks on IA64).</para>
  26.         <para>IPC answer box associated per task</para>
  27.     </section>
  28.     <section>
  29.         <title>Memory management</title>
  30.         <para>
  31.         Zones - linked list (not many zones, so we can afford it. Can be replaced with B-tree in the future)
  32.         Number of zones depends on HW tables. Describe zone allocation/deallocation algoritm
  33.         </para>
  34.         <para>Page tables. 4 level hierarchical and hash directly supported. B+ Tree can be implemented.</para>
  35.         <para>For paging there is an abstract layer</para>
  36.         <para>TLB shootdown implementation (update TLB upon mapping update/remove).
  37.         TLB shootdown ASID/ASID:PAGE/ALL.
  38.         TLB shootdown requests can come in asynchroniously
  39.         so there is a cache of TLB shootdown requests. Upon cache overflow TLB shootdown ALL is executed</para>
  40.        
  41.         <para>
  42.             Address spaces. Address space area (B+ tree). Only for uspace. Set of syscalls (shrink/extend etc).
  43.             Special address space area type - device - prohibits shrink/extend syscalls to call on it.
  44.             Address space has link to mapping tables (hierarchical - per Address space, hash - global tables).
  45.         </para>
  46.     </section>
  47. </chapter>
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