12 <concept id="GUID-A188606F-4A8E-5A85-A241-E15219960EFA" xml:lang="en"><title>Loader

    12 <concept id="GUID-A188606F-4A8E-5A85-A241-E15219960EFA" xml:lang="en"><title>Loader Overview</title><shortdesc>This topic describes the overview, purpose, key concepts

    13 Overview</title><shortdesc>This topic describes the overview, purpose, key concepts and architecture

    13 and architecture of loader.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 of loader.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    20 <section id="GUID-E36370EC-CD5E-54AE-AD62-2BA3B70F5379"><title>Purpose</title> <p>The

    19 <section id="GUID-E36370EC-CD5E-54AE-AD62-2BA3B70F5379"><title>Purpose</title> <p>The loader makes EXEs and DLLs ready to run. </p> <p>The build

    21 loader makes EXEs and DLLs ready to run. </p> <p>The build tools compile the

    20 tools compile the source code into an executable file. An executable

    22 source code into an executable file. An executable file is called a binary.

    21 file is called a binary. The build tools arrange the compiled code

    23 The build tools arrange the compiled code into EXEs and DLLs. The source code,

    22 into EXEs and DLLs. The source code, header files and other information

    24 header files and other information that defines an executable file is defined

    23 that defines an executable file is defined in an mmp file. The loader

    25 in an mmp file. The loader applies relocation information to the code and

    24 applies relocation information to the code and data sections of EXEs

    26 data sections of EXEs and DLLs. The loader also loads DLLs that are referred

    25 and DLLs. The loader also loads DLLs that are referred to by other

    27 to by other EXEs and DLLs. EXEs and DLLs can then run in the process into

    26 EXEs and DLLs. EXEs and DLLs can then run in the process into which

    28 which they are loaded. </p> </section>

    27 they are loaded. </p> </section>

    29 <section id="GUID-89A8CABD-6B31-5D10-87F6-922CCFB83186"><title>Key concepts</title> <p><b>The loader server</b> </p> <p>The Symbian platform loader is a server.

    28 <section id="GUID-89A8CABD-6B31-5D10-87F6-922CCFB83186"><title>Key

    30 The loader server has no public client interface. The client interface is

    29 concepts</title> <p><b>The loader server</b> </p> <p>The Symbian platform loader is a

    31 internal to Symbian platform. Requests to load an EXE or a DLL are passed

    30 server. The loader server has no public client interface. The client

    32 to the loader when you do the following: </p> <ul>

    31 interface is internal to Symbian platform. Requests to load an EXE

    33 <li id="GUID-5DFBB7F5-2F30-50C7-9144-3D6D85C0ACA1"><p>start a new process

    32 or a DLL are passed to the loader when you do the following: </p> <ul>

    34 - a call to <xref href="GUID-9DD1EA2B-DC59-315C-8E9C-CE6D9461B695.dita#GUID-9DD1EA2B-DC59-315C-8E9C-CE6D9461B695/GUID-DD214BA3-907E-3C7F-93C6-924A9A115A02"><apiname>RProcess::Create()</apiname></xref>  </p> </li>

    33 <li id="GUID-5DFBB7F5-2F30-50C7-9144-3D6D85C0ACA1"><p>start a new

    35 <li id="GUID-B88FC041-7643-5CA0-9796-A51E64CAA1DF"><p>load a DLL - a call

    34 process - a call to <xref href="GUID-9DD1EA2B-DC59-315C-8E9C-CE6D9461B695.dita#GUID-9DD1EA2B-DC59-315C-8E9C-CE6D9461B695/GUID-DD214BA3-907E-3C7F-93C6-924A9A115A02"><apiname>RProcess::Create()</apiname></xref>  </p> </li>

    36 to <xref href="GUID-25327159-83D6-3507-B187-09EA4BB3727F.dita#GUID-25327159-83D6-3507-B187-09EA4BB3727F/GUID-4F1B2717-D34F-32A4-B6E6-03D0533186A3"><apiname>RLibrary::Load()</apiname></xref>  </p> </li>

    35 <li id="GUID-B88FC041-7643-5CA0-9796-A51E64CAA1DF"><p>load a DLL -

    37 <li id="GUID-A7578989-6BDB-5CEA-B3C3-0B5A08E57166"><p>load a logical device

    36 a call to <xref href="GUID-25327159-83D6-3507-B187-09EA4BB3727F.dita#GUID-25327159-83D6-3507-B187-09EA4BB3727F/GUID-4F1B2717-D34F-32A4-B6E6-03D0533186A3"><apiname>RLibrary::Load()</apiname></xref>  </p> </li>

    38 driver - a call to <xref href="GUID-C197C9A7-EA05-3F24-9854-542E984C612D.dita#GUID-C197C9A7-EA05-3F24-9854-542E984C612D/GUID-AE0D51B7-7ADC-3C9F-ACAA-8F6D9EA0AEFA"><apiname>User::LoadLogicalDevice()</apiname></xref>. A logical

    37 <li id="GUID-A7578989-6BDB-5CEA-B3C3-0B5A08E57166"><p>load a logical

    39 device driver is a type of DLL. </p> </li>

    38 device driver - a call to <xref href="GUID-C197C9A7-EA05-3F24-9854-542E984C612D.dita#GUID-C197C9A7-EA05-3F24-9854-542E984C612D/GUID-AE0D51B7-7ADC-3C9F-ACAA-8F6D9EA0AEFA"><apiname>User::LoadLogicalDevice()</apiname></xref>. A logical device driver is a type of DLL. </p> </li>

    40 <li id="GUID-34DC54FE-FCEF-5F83-B205-9BA5B7140680"><p>load a physical device

    39 <li id="GUID-34DC54FE-FCEF-5F83-B205-9BA5B7140680"><p>load a physical

    41 driver - a call to <xref href="GUID-C197C9A7-EA05-3F24-9854-542E984C612D.dita#GUID-C197C9A7-EA05-3F24-9854-542E984C612D/GUID-A0F4BF4A-9C58-3E5E-88E1-6D98597DDA18"><apiname>User::LoadPhysicalDevice()</apiname></xref>. A physical

    40 device driver - a call to <xref href="GUID-C197C9A7-EA05-3F24-9854-542E984C612D.dita#GUID-C197C9A7-EA05-3F24-9854-542E984C612D/GUID-A0F4BF4A-9C58-3E5E-88E1-6D98597DDA18"><apiname>User::LoadPhysicalDevice()</apiname></xref>. A physical device driver is a type of DLL. </p> </li>

    42 device driver is a type of DLL. </p> </li>

    41 <li id="GUID-51318E5E-4534-589B-B4BD-92D73F832A6F"><p>load a file

    43 <li id="GUID-51318E5E-4534-589B-B4BD-92D73F832A6F"><p>load a file system -

    42 system - a call to <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-51353BE2-9133-39F5-83F3-A5DB88D858CA"><apiname>RFs::AddFileSystem()</apiname></xref>. A file

    44 a call to <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-51353BE2-9133-39F5-83F3-A5DB88D858CA"><apiname>RFs::AddFileSystem()</apiname></xref>. A file system is a type

    43 system is a type of DLL. A call to <codeph>RFs::AddFileSystem()</codeph> requires DiskAdmin capability. See <xref href="GUID-99D8A4E8-BC4F-39FF-A3DF-832CF0411629.dita"><apiname>ECapabilityDiskAdmin</apiname></xref>. </p> </li>

    45 of DLL. A call to <codeph>RFs::AddFileSystem()</codeph> requires DiskAdmin

    44 <li id="GUID-8394C231-341B-5EA6-B9C2-01F75685813D"><p>load a file

    45 server extension - call to <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-D45FD363-EEF9-3F77-8FA1-49270D8E89A0"><apiname>RFs::AddExtension()</apiname></xref>.

    46 A file server extension is a type of DLL. This function requires DiskAdmin

    47 <li id="GUID-8394C231-341B-5EA6-B9C2-01F75685813D"><p>load a file server extension

    48 <li id="GUID-F1889916-80EB-55B6-BEAF-F66164F3838C"><p>load a locale

    48 - call to <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita#GUID-E263C747-946F-35AA-9F1D-41833BD350FC/GUID-D45FD363-EEF9-3F77-8FA1-49270D8E89A0"><apiname>RFs::AddExtension()</apiname></xref>. A file server extension

    49 - a call to <xref href="GUID-454ACAB5-1573-323C-820E-AF542B149D2A.dita#GUID-454ACAB5-1573-323C-820E-AF542B149D2A/GUID-9F04584E-DD0B-39CE-8666-88F67F3B83BF"><apiname>TExtendedLocale::LoadLocale()</apiname></xref>. </p> </li>

    49 is a type of DLL. This function requires DiskAdmin capability. See <xref href="GUID-99D8A4E8-BC4F-39FF-A3DF-832CF0411629.dita"><apiname>ECapabilityDiskAdmin</apiname></xref>. </p> </li>

    50 </ul> <p><b>Version numbers</b> </p> <p><b>The reason for version numbers</b> </p> <p>More than one version

    50 <li id="GUID-F1889916-80EB-55B6-BEAF-F66164F3838C"><p>load a locale - a call

    51 of an EXE can exist on a device at the same time. More than one version

    51 to <xref href="GUID-454ACAB5-1573-323C-820E-AF542B149D2A.dita#GUID-454ACAB5-1573-323C-820E-AF542B149D2A/GUID-9F04584E-DD0B-39CE-8666-88F67F3B83BF"><apiname>TExtendedLocale::LoadLocale()</apiname></xref>. </p> </li>

    52 of a DLL can exist on a device at the same time. A device can store

    52 </ul> <p><b>Version

    53 versions of an EXE or DLL that are not compatible with an older version

    53 numbers</b> </p> <p><b>The

    54 of that EXE or DLL. </p> <p>A version number is a set of two numbers.

    54 reason for version numbers</b> </p> <p>More than one version of an EXE can

    55 The loader uses these numbers to identify copies of the executable

    55 exist on a device at the same time. More than one version of a DLL can exist

    56 file. The two numbers are called the major version number and the

    56 on a device at the same time. A device can store versions of an EXE or DLL

    57 minor version number. The build tools encode the two numbers into

    57 that are not compatible with an older version of that EXE or DLL. </p> <p>A

    58 the header of the executable file. When a DLL is built, the version

    58 version number is a set of two numbers. The loader uses these numbers to identify

    59 numbers are encoded into the import library. </p> <p><b>The structure of version information</b> </p> <p>DLLs are the

    59 copies of the executable file. The two numbers are called the major version

    60 most common users of versions. You assign new values to the version

    60 number and the minor version number. The build tools encode the two numbers

    61 numbers of a DLL when you change the published API of the DLL. Symbian

    61 into the header of the executable file. When a DLL is built, the version numbers

    62 recommends the following procedure: </p> <ul>

    62 are encoded into the import library. </p> <p><b>The

    63 <li id="GUID-A3D6B7C6-E48E-5374-8EFE-29EB129FEE04"><p>change the minor

    63 structure of version information</b> </p> <p>DLLs are the most common users

    64 version number if you make a change to a DLL that is backward compatible.

    64 of versions. You assign new values to the version numbers of a DLL when you

    65 An example is a new function in the DLL. </p> </li>

    65 change the published API of the DLL. Symbian recommends the following procedure: </p> <ul>

    66 <li id="GUID-F6813400-1E6A-58B9-8360-7FD364F2153A"><p>change the major

    66 <li id="GUID-A3D6B7C6-E48E-5374-8EFE-29EB129FEE04"><p>change the minor version

    67 version number if you make a change to a DLL that breaks an interface.

    67 number if you make a change to a DLL that is backward compatible. An example

    68 An example is the removal of a function or a change to the signature

    68 is a new function in the DLL. </p> </li>

    69 of a function. An interface break is disruptive and must be prevented. </p> </li>

    69 <li id="GUID-F6813400-1E6A-58B9-8360-7FD364F2153A"><p>change the major version

    70 </ul> <p>The major and minor version numbers are defined in the <filepath>.mmp</filepath> file that defines the source code, header files and

    70 number if you make a change to a DLL that breaks an interface. An example

    71 other options that apply to the executable file. </p> <p>If you do

    71 is the removal of a function or a change to the signature of a function. An

    72 not specify version numbers, the build tools apply the following default

    72 interface break is disruptive and must be prevented. </p> </li>

    73 values: </p> <ul>

    73 </ul> <p>The major and minor version numbers are defined in the <filepath>.mmp</filepath> file

    74 <li id="GUID-CBF4D098-3A83-53E6-9E54-0A9B487D6E22"><p>Major version

    74 that defines the source code, header files and other options that apply to

    75 number : 10 </p> </li>

    75 the executable file. </p> <p>If you do not specify version numbers, the build

    76 <li id="GUID-46E7516E-988B-5F92-9877-FEE17D3F26A7"><p>Minor version

    76 tools apply the following default values: </p> <ul>

    77 number : 0 </p> </li>

    77 <li id="GUID-CBF4D098-3A83-53E6-9E54-0A9B487D6E22"><p>Major version number

    78 </ul> <p>The major version number and the minor version number are

    78 : 10 </p> </li>

    79 stored in the header of an EXE and DLL. The two numbers are stored

    79 <li id="GUID-46E7516E-988B-5F92-9877-FEE17D3F26A7"><p>Minor version number

    80 in a single 32 bit value. The high 16 bits hold the major version

    80 : 0 </p> </li>

    81 number. The low 16 bits hold the minor version number. </p> <p>When

    81 </ul> <p>The major version number and the minor version number are stored

    82 you build a DLL, the build tools encode the version numbers into the

    82 in the header of an EXE and DLL. The two numbers are stored in a single 32

    83 filename of the import library (the <filepath>.lib</filepath> file).

    83 bit value. The high 16 bits hold the major version number. The low 16 bits

    84 The build tools also create an import library that does not have the

    84 hold the minor version number. </p> <p>When you build a DLL, the build tools

    85 version numbers encoded as part of the filename.The following example

    85 encode the version numbers into the filename of the import library (the <filepath>.lib</filepath> file).

    86 shows how the version numbers are encoded in the filename. The major

    86 The build tools also create an import library that does not have the version

    87 version number is (decimal) 11 and the minor version number is (decimal)

    87 numbers encoded as part of the filename.The following example shows how the

    88 2. The version numbers in the filename are in hexadecimal. </p> <p> <filepath>abcdsrv{000B0002}.lib</filepath>  </p> <p>Notes: </p> <ul>

    88 version numbers are encoded in the filename. The major version number is (decimal)

    89 <li id="GUID-7DC90016-5A54-5939-84B1-DDB0B2D4D9F5"><p>The left bracket

    89 11 and the minor version number is (decimal) 2. The version numbers in the

    90 and the right bracket are part of the name. </p> </li>

    90 filename are in hexadecimal. </p> <p> <filepath>abcdsrv{000B0002}.lib</filepath>  </p> <p>Notes: </p> <ul>

    91 <li id="GUID-BC291976-EB6D-59D2-8941-64F6ED3AC191"><p>The first four

    91 <li id="GUID-7DC90016-5A54-5939-84B1-DDB0B2D4D9F5"><p>The left bracket and

    92 digits after the open bracket are the hexadecimal representation of

    92 the right bracket are part of the name. </p> </li>

    93 the major version number. </p> </li>

    93 <li id="GUID-BC291976-EB6D-59D2-8941-64F6ED3AC191"><p>The first four digits

    94 <li id="GUID-51590778-985F-5DCC-9191-E937B1058F51"><p>The second four

    94 after the open bracket are the hexadecimal representation of the major version

    95 digits are the hexadecimal representation of the minor version number. </p> </li>

    95 number. </p> </li>

    96 </ul> <p>The build tools do not encode the version numbers in the

    96 <li id="GUID-51590778-985F-5DCC-9191-E937B1058F51"><p>The second four digits

    97 filename of the executable file. </p> <p><b>Loader search rules</b> </p> <p>EXEs and DLLs can exist on more

    97 are the hexadecimal representation of the minor version number. </p> </li>

    98 than one drive. There can be more than one version of an EXE and more

    98 </ul> <p>The build tools do not encode the version numbers in the filename

    99 than one version of a DLL. The loader uses search rules to select

    99 of the executable file. </p> <p><b>Loader

   100 the EXE and DLL to load. </p> <p>See <xref href="GUID-D8837969-74D0-5E17-AD42-3F10DD1FD5BF.dita">Loader search rules</xref>  </p> <p><b>Emulator</b> </p> <p>Version numbers are stored in import files

   100 search rules</b> </p> <p>EXEs and DLLs can exist on more than one drive. There

   101 for DLLs that run on devices and the emulator. Version numbers change

   101 can be more than one version of an EXE and more than one version of a DLL.

   102 how the loader functions on devices, but not in the emulator. You

   102 The loader uses search rules to select the EXE and DLL to load. </p> <p>See <xref href="GUID-D8837969-74D0-5E17-AD42-3F10DD1FD5BF.dita">Loader search rules</xref>  </p> <p><b>Emulator</b> </p> <p>Version numbers are stored in import files for DLLs

   103 cannot encode the version numbers in the import library file name

   103 that run on devices and the emulator. Version numbers change how the loader

   104 on the emulator. </p> <p><b>Tools support</b> </p> <p>Use the build tools to apply version

   104 functions on devices, but not in the emulator. You cannot encode the version

   105 numbers to EXEs and DLLs. You specify version numbers in the <filepath>.mmp</filepath> file that describes the EXE or DLL. </p> <p>See also <uicontrol>MMP file syntax</uicontrol> in <uicontrol>Symbian Tools Guide &gt; Building

   105 numbers in the import library file name on the emulator. </p> <p><b>Tools support</b> </p> <p>Use the build tools to apply version numbers

   106  &gt; Symbian Build System (SBSv1) &gt; Build tools reference</uicontrol>.</p> </section>

   106 to EXEs and DLLs. You specify version numbers in the <filepath>.mmp</filepath> file

   107 that describes the EXE or DLL. </p> <p>See also <xref href="GUID-BBBB5000-90A2-503A-9521-2FC6DEC69DC8.dita">mmp

   108 file syntax</xref> and <xref href="GUID-B21141D4-3BFE-59C9-8D5F-147A93BE1C95.dita">Build

   109 tools guide</xref>. </p> </section>

   111 relationships</title> <p>The loader is a server that runs in a separate thread

   108 relationships</title> <p>The loader is a server that runs in a separate

   112 in the file server process. The loader is built as part of the file server. </p> <p>The

   109 thread in the file server process. The loader is built as part of

   113 loader server starts when the file server starts. The file server starts after

   110 the file server. </p> <p>The loader server starts when the file server

   114 the kernel is loaded at system start. </p> <p>The loader runs on the user

   111 starts. The file server starts after the kernel is loaded at system

   115 side, but calls the kernel for services that are not available to general

   112 start. </p> <p>The loader runs on the user side, but calls the kernel

   116 applications. Examples of services are process creation and code segment creation.

   113 for services that are not available to general applications. Examples

   117 A code segment is an object that represents a piece of code loaded into RAM.

   114 of services are process creation and code segment creation. A code

   118 A code segment also represents a piece of code that runs directly from ROM.

   115 segment is an object that represents a piece of code loaded into RAM.

   119 The kernel services that the loader uses are protected. The file server process

   116 A code segment also represents a piece of code that runs directly

   120 only is allowed to access these services. </p> <p>The following picture is

   117 from ROM. The kernel services that the loader uses are protected.

   121 an example of program flow. In this example, a client calls <xref href="GUID-25327159-83D6-3507-B187-09EA4BB3727F.dita#GUID-25327159-83D6-3507-B187-09EA4BB3727F/GUID-4F1B2717-D34F-32A4-B6E6-03D0533186A3"><apiname>RLibrary::Load()</apiname></xref>,

   118 The file server process only is allowed to access these services. </p> <p>The following picture is an example of program flow. In this

   122 which exists in <filepath>euser.dll</filepath>. Internal functions make client-server

   119 example, a client calls <xref href="GUID-25327159-83D6-3507-B187-09EA4BB3727F.dita#GUID-25327159-83D6-3507-B187-09EA4BB3727F/GUID-4F1B2717-D34F-32A4-B6E6-03D0533186A3"><apiname>RLibrary::Load()</apiname></xref>, which

   123 calls to the loader server. The loader server code exists in <filepath>efile.exe</filepath>.

   120 exists in <filepath>euser.dll</filepath>. Internal functions make

   124 The loader server uses kernel services. </p> <fig id="GUID-5FCAE81A-19BC-5BE7-89D2-096A87735381">

   121 client-server calls to the loader server. The loader server code exists

   125 <image href="GUID-2735BDAF-295F-5F1E-8925-8F4212D95CD1_d0e264145_href.png" placement="inline"/>

   122 in <filepath>efile.exe</filepath>. The loader server uses kernel services. </p> <fig id="GUID-5FCAE81A-19BC-5BE7-89D2-096A87735381">

   123 <image href="GUID-2735BDAF-295F-5F1E-8925-8F4212D95CD1_d0e269008_href.png" placement="inline"/>