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Type 3 image, multiple load regions and non-contiguous execution regions

A Type 3 image consists of multiple load regions in load view and multiple execution regions in execution view. They are similar to images of Type 2 except that the single load region in Type 2 is now split into multiple load regions.

You can relocate and split load regions using the following linker options:

--reloc

The combination --reloc --split makes an image similar to simple Type 3, but the two load regions now have the RELOC attribute.

Note

You cannot use this option if an object file contains execute-only sections.

--ro_base=address1

Specifies the load and execution address of the region containing the RO output section.

--rw_base=address2

Specifies the load and execution address for the region containing the RW output section.

--split

Splits the default single load region that contains the RO and RW output sections into two load regions. One load region contains the RO output section and one contains the RW output section.

Example for multiple load regions

The following example shows the scatter-loading description equivalent to using --ro_base=0x010000 --rw_base=0x040000 --split:

LR_1 0x010000     ; The first load region is at 0x010000.
{    
    ER_RO +0      ; The address is 0x010000.
    {
        * (+RO)
    }
}
LR_2 0x040000     ; The second load region is at 0x040000.
{
    ER_RW +0      ; The address is 0x040000.
    {
        * (+RW)   ; All RW sections are placed consecutively into this region.
    }
    ER_ZI +0      ; The address is 0x040000 + size of ER_RW region.
    {
        * (+ZI)   ; All ZI sections are placed consecutively into this region.
    }
}

In this example:

  • This description creates an image with two load regions, named LR_1 and LR_2, that have load addresses 0x010000 and 0x040000.

  • The image has three execution regions, named ER_RO, ER_RW and ER_ZI, that contain the RO, RW, and ZI output sections respectively. The execution address of ER_RO is 0x010000.

  • The ER_RW execution region is not contiguous with ER_RO, because its execution address is 0x040000.

  • The ER_ZI execution region is placed immediately after ER_RW.

Relocatable load regions example variant

This Type 3 image also consists of two load regions in load view and three execution regions in execution view. However, --reloc specifies that the two load regions now have the RELOC attribute.

The following example shows the scatter-loading description equivalent to using --ro_base 0x010000 --rw_base 0x040000 --reloc --split:

LR_1 0x010000 RELOC
{
     ER_RO + 0
     {
         * (+RO)
     }
} 
LR2 0x040000 RELOC
{
     ER_RW + 0
     {
         * (+RW)
     }
     ER_ZI +0
     { 
         * (+ZI)
     }
}