ARM Compiler toolchain Using the Linker - ARM Information Center

Features of the Base Platform linking model
11.1 Restrictions on the use of scatter files with the Base Platform model
The Base Platform model supports scatter files. Although there are no restrictions on the
keywords you can use in a scatter file, there are restrictions on the types of scatter files you can
use:
• A load region marked with the RELOC attribute must contain only execution regions with a
relative base address of +offset. The following examples show valid and invalid scatter
files using the RELOC attribute and +offset relative base address:
Example 11-1 Valid scatter file example using RELOC and +offset
# This is valid. All execution regions have +offset addresses.
LR1 0x8000 RELOC
{
ER_RELATIVE +0
{
*(+RO)
}
}
Example 11-2 Invalid scatter file example using RELOC and +offset
# This is not valid. One execution region has an absolute base address.
LR1 0x8000 RELOC
{
ER_RELATIVE +0
{
*(+RO)
}
ER_ABSOLUTE 0x1000
{
*(+RW)
}
}
• Any load region that requires a PLT section must contain at least one execution region
containing code, that is not marked OVERLAY. This execution region is used to hold the PLT
section. An OVERLAY region cannot be used as the PLT must remain in memory at all times.
The following examples show valid and invalid scatter files that define execution regions
requiring a PLT section:
Example 11-3 Valid scatter file example for a load region that requires a PLT section
# This is valid. ER_1 contains code and is not OVERLAY.
LR_NEEDING_PLT 0x8000
{
ER_1 +0
{
*(+RO)
}
}
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