Mercurial Mercurial > oss > MCL > sftools > depl > docscontent / annotate
summary | shortlog | changelog | graph | tags | bookmarks | branches | files | changeset | file | latest | revisions | annotate | diff | comparison | raw | help
Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Adaptation/GUID-7C533836-0D27-5519-BC1D-7153AC8BE4C0.dita
author Graeme Price <GRAEME.PRICE@NOKIA.COM>
Fri, 15 Oct 2010 14:32:18 +0100
changeset 15 307f4279f433
permissions -rw-r--r--
Initial contribution of the Adaptation Documentation.
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
15
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
     1
 
<?xml version="1.0" encoding="utf-8"?>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
     2
 
<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
     3
 
<!-- This component and the accompanying materials are made available under the terms of the License
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
     4
 
"Eclipse Public License v1.0" which accompanies this distribution,
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
     5
 
and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
     6
 
<!-- Initial Contributors:
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
     7
 
    Nokia Corporation - initial contribution.
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
     8
 
Contributors:
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
     9
 
-->
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    10
 
<!DOCTYPE concept
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    11
 
  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    12
 
<concept id="GUID-7C533836-0D27-5519-BC1D-7153AC8BE4C0" xml:lang="en"><title>Media
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    13
 
Driver Guide</title><shortdesc>Describes the issues that need to be considered, when writing a
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    14
 
media device driver for a writable data demand paging environment. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    15
 
<section id="GUID-46C98F8A-1486-4FAD-918D-3FB0E7CA372E"><title>Purpose</title> <p>This
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    16
 
document explains the points that have to be considered when writing a media
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    17
 
driver in an environment that uses writable data paging. </p> </section>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    18
 
<section id="GUID-1A89843E-B174-49F0-87D8-A8ADBE933A54"><title>Issues to consider</title> <p>The
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    19
 
main issue to consider when writing a media device driver for a writable demand
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    20
 
paging environment is to avoid page faults from occurring in DFCs, since this
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    21
 
can lead to a deadlock condition between the driver and the client process. </p> <p>This
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    22
 
can be avoided using the following methods: </p> <ul>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    23
 
<li id="GUID-76EF65C9-63E8-5C9B-99CD-A8BFBBA9B68C"><p>Use shared chunks. </p> <p>Shared
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    24
 
chunks are memory areas that are accessible by both kernel-side and user-side
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    25
 
and they are never paged. </p> <p>This is the best solution for drivers that
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    26
 
involve fast throughput such as media drivers. </p> </li>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    27
 
<li id="GUID-32198DFA-CCF9-5260-A677-88F5B9FBF315"><p>Use synchronous rather
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    28
 
than asynchronous data transfer </p> <p>This could be done by implementing
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    29
 
the following steps: </p> <ol id="GUID-8C359B63-D166-5A54-8772-811FC2656E66">
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    30
 
<li id="GUID-018F2121-A883-5B2F-B70E-C77069B3F1A1"><p>The client requests
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    31
 
a notification when data is available. </p> </li>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    32
 
<li id="GUID-0FC1D31E-4937-572B-BD80-99DDFABCC0BF"><p>The data arrives. </p> </li>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    33
 
<li id="GUID-6B47B0FA-8921-5B12-A71C-0E66DD286FD1"><p>The driver writes data
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    34
 
into an internal buffer and completes the client request. </p> </li>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    35
 
<li id="GUID-14E4D83B-7361-5DE4-90BF-B9CEB658FF1D"><p>The client makes a read
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    36
 
request. </p> </li>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    37
 
<li id="GUID-FF2A912E-3FBB-5671-ADBE-090FED1CD873"><p>The driver writes the
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    38
 
data back to the client in the client thread context. </p> </li>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    39
 
</ol> <p>This approach is easy to implement, however it requires the buffering
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    40
 
of data. </p> </li>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    41
 
<li id="GUID-08F4A4BD-699B-5800-BD2D-78A5406C19EB"><p>Use the <xref href="GUID-066868C5-12F8-59A5-A2DE-FEDC4F459771.dita">flexible
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    42
 
memory model</xref>  </p> <p>This provides the ability for the memory to be
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    43
 
mapped into a drive's address space as unpaged. </p> <p>This is an alternative
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    44
 
to the use of shared chunks. </p> <p>However, this is not supported on the
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    45
 
moving or multiple memory models. </p> </li>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    46
 
</ul> </section>
307f4279f433 Initial contribution of the Adaptation Documentation.
Graeme Price <GRAEME.PRICE@NOKIA.COM>
parents:
diff changeset 
    47
 
</conbody></concept>
MCL/sftools/depl/docscontent