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<concept id="GUID-A3449F37-89BB-5208-8FD5-F4DF73F7E71A" xml:lang="en"><title>System
Startup Overview</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<section id="GUID-C41A0540-2C28-4CCC-B8AA-8236C68CEB18"><title> Configuring
and Controlling a device's boot process </title> <p>Whenever a Symbian device
is powered up a number of things have to happen before it is ready to be used.
A number of processes and applications have to be started and certain tasks
performed. </p> <p>The System Starter and its related components control the
startup process. This guide describes what the System Starter does and how
it may be configured. Configuration is the responsibility of device manufacturers.
A manufacturer may choose to enable operators, third parties and users to
extend the startup configuration. </p> <p>There are numerous considerations
when configuring device startup. These include: </p> <ul>
<li id="GUID-5BA1769D-D1FC-59A4-87F6-30D031443CD9"><p>which processes, tasks
and applications are required, </p> </li>
<li id="GUID-48D7345B-0D3B-5ADA-A646-A3DAC85FE4F5"><p>the sequence of, and
inter-dependencies between, activities, </p> </li>
<li id="GUID-9C7A919A-8C67-5DC0-BDD8-D1DC12AE0636"><p>the user experience, </p> </li>
<li id="GUID-9F2C5CCC-EAD6-5AD6-8B85-7EB459F385BA"><p>the impact on manufacturing
and testing, </p> </li>
<li id="GUID-7212D20D-2A6C-51BC-A3B4-23FAF4CA5EC0"><p>operators' customisation
requirements, </p> </li>
<li id="GUID-1D75BFB9-9E0C-5E60-8473-278D3ABCF7B7"><p>users' customisation
requirements, </p> </li>
<li id="GUID-41225C9C-047B-59BF-A670-0981A73BF6FC"><p>what to do when something
goes wrong </p> <p>and </p> </li>
<li id="GUID-5E519AE8-3268-5C2B-A623-2E99229947F8"><p>aftermarket applications </p> </li>
</ul> <p><b>Processes and Applications </b> </p> <p>In the interest of readability
this document frequently<b> uses the terms application and process interchangeably</b>.
Unless specifically stated otherwise you may assume that the term used refers
to both. </p> </section>
<section id="GUID-528B2FD1-7233-413A-81C8-5064095135AB"><title>Static Startup
Configuration</title> <p>The System Starter is automatically invoked as part
of the boot process once the file system has been mounted. It works by processing
a list of instructions in sequence. The list is referred to as a Static Startup
Configuration, or SSC. In practical terms the SSC is defined in a resource
file and is built into the ROM. </p> <p>A fundamental feature of the SSC is
that it allows the start up procedure to be optimised. Though the commands
are processed in sequence their effect is to perform tasks not only in <b>sequence</b> (wait
for the application or process to initialise before continuing) but also in <b>parallel</b> (do
not wait for initialisation) and <b>at the optimum time</b> (wait until conditions
are right). </p> <p>For further information on the contents of an SSC see: </p> <ul>
<li id="GUID-1F8911D9-F92B-5A4F-8548-942842A7ED2A"><p><xref href="GUID-57F38146-1DA3-5657-ADF4-76DF740363C5.dita">Static
Startup Configuration</xref>  </p> </li>
</ul> <p>Though an SSC cannot be changed, a number of SSCs may be included
in a ROM. This allows a device to be started with one of a number of different
configurations, i.e. to be booted into different <b>modes</b>. </p> <ul>
<li id="GUID-92E0E027-8A4F-55A5-AC48-4252164E2E77"><p>The mode determines
which SSC the System Starter uses to start the system. Symbian has defined
(and reserved) a number of Startup Modes (for test and reference purposes):
Full, Emulator, Emergency, Battery charge &amp; Test. Device manufacturers
may use their own startup modes and reserve their own unique range of values
by sending an email to the Device Services package mailing list (<xref href="mailto:td-os_base_services-dev@lists.symbian.org" scope="external">td-os_base_services-dev@lists.symbian.org</xref>) specifying: </p> <ol id="GUID-E4D9A3AB-4BD5-5E5E-8B70-8E6435842F06">
<li id="GUID-9F4658CA-4DCE-5E88-91FC-AE0F3CA65997"><p>the device manufacturer
name </p> </li>
<li id="GUID-AA1CC293-099A-5534-BA71-3EEE6691BE53"><p>the number of start-up
mode ranges required (each range has 32 values)</p> </li>
</ol> </li>
</ul> <p>SSC files are named <filepath>SCCForStartupModeN.rss</filepath> where
N is the number of the mode. The method of selecting the mode, and therefore
the SSC file, for each startup is defined by the licensee. </p> <p>The degree
to which an SSC can control and optimise the boot process is further enhanced
by the concepts of <b>Startup States</b> and <b>Staged Startup</b>. </p> <p><b> Startup
States</b> </p> <p>An SSC is divided into a series of states which follow
each other sequentially. Those described here are defined by Symbian. Licencees
may add or insert further states by defining them and including them in an
SSC. The Symbian defined states have a certain significance: </p> <ul>
<li id="GUID-4C3113C7-CFAF-59AE-A271-51424F6B2478"><p> <b>The Critical Static
State:</b> This is when the essential ROM based components are started. Nothing
started in this state relies on anything outside the ROM. </p> </li>
<li id="GUID-56754FF8-08A4-56BE-A4C2-A8F2A25AE738"><p> <b> The Critical Dynamic
State:</b> This is when essential non-ROM based components and components
which use non-ROM based files are started. </p> </li>
<li id="GUID-804244EC-006E-5216-B286-D9FC6B9495EA"><p> <b> The Non-critical
State:</b> Components started here are not essential for the basic functionality
of the device. i.e. the phone will be 'up and running' before these components
are started. </p> </li>
</ul><p><b>Staged Startup</b> </p> <p>A further level of startup control and
configuration can be achieved using Staged Startup. This technique enables
components to perform their initialisation procedure as separate stages -
essential earlier, non-essential later. This enables further reduction of
the effective boot time. </p> <p>Applications must be <b>Staged Startup Aware
(SSA)</b> to take advantage of the staged startup facilities. They must register
with the Starter so that they can receive state-change notifications. An SSA
application may perform a <b>stage</b> of its startup during each SSC <b>state</b>. </p> <p>Staged
startup subdivides each state into five ordered domains: Kernel, Base, OS
Services, Application Services and UI Framework (these correspond to the <xref href="http://developer.symbian.org/wiki/index.php/Symbian_System_Model" scope="external">Symbian
System Model</xref>). Each SSA component associates itself with a domain according
to its location in the System Model. Within each state the domains are processed
sequentially. This allows application dependency to be accommodated without
individual applications having to manage these dependencies. </p> </section>
<section id="GUID-F58AE201-31BF-4E36-96B6-50D61A53B9CA"><title>Dynamic Startup
Configuration (DSC) </title> <p>All of the components included in the Static
Startup Configuration are present for the life of the device. Components installed
after the ROM has been built, or after the device has been shipped, may also
be started during boot by being added to a Dynamic Startup Configuration (DSC). </p> <p>One
or more DSCs may be included at various points in an SSC. </p> <p>A run-time
API allows entries to be added to and deleted from a DSC. This means that
aftermarket applications, updates and patches can be inserted automatically
on installation, over the air by a Network Operator, or by the user. </p> <ul>
<li id="GUID-84D36270-880B-56F4-BBD9-5C80F9DA1BEF"><p><xref href="GUID-E3941FAF-988E-5FB3-8E62-84E192E41EA1.dita">How
to use the DSC API</xref>  </p> </li>
</ul> </section>
<section id="GUID-D6D28700-0BAD-4F88-8CE9-2E0330233468"><title>Specifying
action on failure </title> <p>Though system startup is an automatic process,
things can go wrong. In some cases the device can continue to function if
a component fails to start, in others it cannot. Applications can fail to
start or fail after they have started for a variety of reasons. Symbian provides
mechanisms for detecting and handling failure. </p> <p>When an application
is started using an SSC or a DSC several parameters must be specified in its
resource. These include: </p> <ul>
<li id="GUID-4DC8B8DA-FA50-57E9-B1FD-B60991C927C1"><p>a startup method (<codeph>EFireAndForget</codeph>, <codeph>EWaitForStart</codeph>, <codeph>EDeferredWaitForStart</codeph>) </p> </li>
<li id="GUID-8236B8FB-CDD9-544A-91FA-F53231EDEDAF"><p>the number of retries
(attempts to start the application) </p> </li>
<li id="GUID-A9EA3792-BA99-59C8-8AE1-40A34CFAC095"><p>a timeout period (after
which an EWaitForStart startup will be considered to have failed) </p> </li>
<li id="GUID-F9CEA642-4140-5430-9092-C5B70BE9B691"><p>a restart action (<codeph>EIgnoreProcessFailure</codeph>, <codeph>ERestartOS</codeph>, <codeph>ERestartOSWithMode</codeph> - the action to be taken in the event of failure
to rendezvous or failure while running normally.) </p> </li>
<li id="GUID-F737C84D-3BAB-5256-858E-4D9EF9C0AB19"><p>a restart mode (the
phone might restart in a 'Safe Mode', for instance) </p> </li>
<li id="GUID-2030D3D4-D1C6-5E80-B75E-F8F656CA5168"><p>whether to initiate
monitoring after the component has made its rendezvous. </p> </li>
</ul> <p>If, after the <b>timeout period</b> the application has not made
its rendezvous, the platform can make further attempts to start it. If, after
the <b>number of retries</b> specified, it has not succeeded it will take
the specified <b>restart action</b>. If the restart action is <codeph>ERestartOS</codeph> or <codeph>ERestartOSWithMode</codeph> it
will shut down the device and restart it (in the second case in the <b>restart
mode</b> specified). If <b>monitoring</b> is enabled the System Monitor will
continue to monitor the process after a successful rendezvous and, if it stops
unexpectedly at any time, will re-use the same configuration information and
act accordingly. </p> <ul>
<li id="GUID-64BFBF8C-3279-5DE5-9350-19DB7FD5D481"><p><xref href="GUID-4E195F2A-78AE-5664-A115-AD65BF457AB1.dita">How
to use the System Monitor</xref>  </p> </li>
</ul> <p>Note that processes or threads declared 'System Critical' use an
aternative monitoring mechanism, which pre-dates the System Monitor, to restart
the platform, when they fail (see <xref href="GUID-B0E661BC-4058-3256-B9C3-5A4FD52F6DE5.dita#GUID-B0E661BC-4058-3256-B9C3-5A4FD52F6DE5/GUID-AF3E8BE4-FE65-3CCE-8B5A-6C4585BEA2EC"><apiname>RThread::SetCritical()</apiname></xref>).
The System Monitor offers two significant advantages: the ability to restart
the process without restarting the platform, and the option of restarting
in a specified mode. </p> </section>
</conbody></concept>