+++ /dev/null
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->Modifying the Memory Layout</TITLE
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-><DIV
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-><H1
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-><A
-NAME="MODIFYING-THE-MEMORY-LAYOUT">Modifying the Memory Layout</H1
-><P
->Each <SPAN
-CLASS="PRODUCTNAME"
->eCos</SPAN
-> platform package is supplied with linker script
-fragments which describe the location of memory regions on the evaluation
-board and the location of memory sections within these regions.
-The correct linker script fragment is selected and included in the
-<SPAN
-CLASS="PRODUCTNAME"
->eCos</SPAN
-> linker script <TT
-CLASS="FILENAME"
->target.ld</TT
-> when
-<SPAN
-CLASS="PRODUCTNAME"
->eCos</SPAN
-> is built.</P
-><P
->It is not necessary to modify the default memory
-layouts in order to start development with <SPAN
-CLASS="PRODUCTNAME"
->eCos</SPAN
->. However, it will
-be necessary to edit a linker script fragment when the memory map
-of the evaluation board is changed. For example, if additional memory
-is added, the linker must be notified that the new memory is available
-for use. As a minimum, this would involve modifying the length of
-the corresponding memory region. Where the available memory is non-contiguous,
-it may be necessary to declare a new memory region and reassign
-certain linker output sections to the new region.</P
-><P
->Linker script fragments and memory layout header files should
-be edited within the <SPAN
-CLASS="PRODUCTNAME"
->eCos</SPAN
-> install tree. They are
-located at <TT
-CLASS="FILENAME"
->include/pkgconf/mlt_*.*</TT
->.
-Where multiple start-up types are in use, it will be necessary to
-edit multiple linker script fragments and header files. The information
-provided in the header file and the corresponding linker script
-fragment must always match. A typical linker script fragment is
-shown below:</P
-><DIV
-CLASS="EXAMPLE"
-><A
-NAME="AEN2992"><P
-><B
->Example 28-1. <SPAN
-CLASS="PRODUCTNAME"
->eCos</SPAN
-> linker script fragment</B
-></P
-><TABLE
-BORDER="5"
-BGCOLOR="#E0E0F0"
-WIDTH="70%"
-><TR
-><TD
-><PRE
-CLASS="PROGRAMLISTING"
->MEMORY
-{
- rom : ORIGIN = 0x40000000, LENGTH = 0x80000
- ram : ORIGIN = 0x48000000, LENGTH = 0x200000
-}
-
-SECTIONS
-{
- SECTIONS_BEGIN
- SECTION_rom_vectors (rom, 0x40000000, LMA_EQ_VMA)
- SECTION_text (rom, ALIGN (0x1), LMA_EQ_VMA)
- SECTION_fini (rom, ALIGN (0x1), LMA_EQ_VMA)
- SECTION_rodata (rom, ALIGN (0x1), LMA_EQ_VMA)
- SECTION_rodata1 (rom, ALIGN (0x1), LMA_EQ_VMA)
- SECTION_fixup (rom, ALIGN (0x1), LMA_EQ_VMA)
- SECTION_gcc_except_table (rom, ALIGN (0x1), LMA_EQ_VMA)
- SECTION_data (ram, 0x48000000, FOLLOWING (.gcc_except_table))
- SECTION_bss (ram, ALIGN (0x4), LMA_EQ_VMA)
- SECTIONS_END
-}</PRE
-></TD
-></TR
-></TABLE
-></DIV
-><P
->The file consists of two blocks, the <TT
-CLASS="LITERAL"
->MEMORY</TT
-> block
-contains lines describing the address (<TT
-CLASS="LITERAL"
->ORIGIN</TT
->)
-and the size (<TT
-CLASS="LITERAL"
->LENGTH</TT
->) of each memory
-region. The <TT
-CLASS="LITERAL"
->MEMORY</TT
-> block is followed
-by the <TT
-CLASS="LITERAL"
->SECTIONS</TT
-> block which contains
-lines describing each of the linker output sections. Each section
-is represented by a macro call. The arguments of these macros are
-ordered as follows: </P
-><P
-></P
-><OL
-TYPE="1"
-><LI
-><P
->The memory region in which the section will finally
- reside.</P
-></LI
-><LI
-><P
->The final address (
-<TT
-CLASS="LITERAL"
->VMA</TT
->
-) of the section. This is expressed using one of the following forms:</P
-><P
-></P
-><DIV
-CLASS="VARIABLELIST"
-><DL
-><DT
-><SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->n</I
-></SPAN
-></DT
-><DD
-><P
->at the absolute address specified by the
- unsigned integer <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->n</I
-></SPAN
-></P
-></DD
-><DT
->ALIGN (<SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->n</I
-></SPAN
->)</DT
-><DD
-><P
->following the final location of the previous section
- with alignment to the next <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->n</I
-></SPAN
->-byte
- boundary</P
-></DD
-></DL
-></DIV
-></LI
-><LI
-><P
->The initial address (<TT
-CLASS="LITERAL"
->LMA</TT
->)
- of the section. This is expressed using one of the
- following forms:</P
-><P
-></P
-><DIV
-CLASS="VARIABLELIST"
-><DL
-><DT
->LMA_EQ_VMA</DT
-><DD
-><P
->the <TT
-CLASS="LITERAL"
->LMA</TT
->
- equals the <TT
-CLASS="LITERAL"
->VMA</TT
-> (no relocation)</P
-></DD
-><DT
->AT (<SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->n</I
-></SPAN
->)</DT
-><DD
-><P
->at the absolute address specified by the
- unsigned integer <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->n</I
-></SPAN
-></P
-></DD
-><DT
->FOLLOWING (.<SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->name</I
-></SPAN
->)</DT
-><DD
-><P
->following the initial location of section
- <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->name</I
-></SPAN
-></P
-></DD
-></DL
-></DIV
-></LI
-></OL
-><P
->In order to maintain compatibility with linker script
- fragments and header files exported by the
- <SPAN
-CLASS="PRODUCTNAME"
->eCos</SPAN
-> <SPAN
-CLASS="APPLICATION"
->Configuration Tool</SPAN
->, the use
- of other expressions within these files is not
- recommended.</P
-><P
->Note that the names of the linker output sections will vary
-between target architectures. A description of these sections can
-be found in the specific <SPAN
-CLASS="PRODUCTNAME"
->GCC</SPAN
-> documentation for
-your architecture.</P
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