SPRUIG8J January 2018 – March 2024
You can allocate a section into a memory range that is defined by the MEMORY directive (see Section 12.5.4). This example names ranges and links sections into them:
MEMORY
{
SLOW_MEM (RIX) : origin = 0x00000000, length = 0x00001000
FAST_MEM (RWIX) : origin = 0x03000000, length = 0x00000300
}
SECTIONS
{
.text : > SLOW_MEM
.data : > FAST_MEM ALIGN(128)
.bss : > FAST_MEM
}In this example, the linker places .text into the area called SLOW_MEM. The .data and .bss output sections are allocated into FAST_MEM. You can align a section within a named memory range; the .data section is aligned on a 128-byte boundary within the FAST_MEM range.
Similarly, you can link a section into an area of memory that has particular attributes. To do this, specify a set of attributes (enclosed in parentheses) instead of a memory name. Using the same MEMORY directive declaration, you can specify:
SECTIONS
{
.text: > (X) /* .text --> executable memory */
.data: > (RI) /* .data --> read or init memory */
.bss : > (RW) /* .bss --> read or write memory */
}In this example, the .text output section can be linked into either the SLOW_MEM or FAST_MEM area because both areas have the X attribute. The .data section can also go into either SLOW_MEM or FAST_MEM because both areas have the R and I attributes. The .bss output section, however, must go into the FAST_MEM area because only FAST_MEM is declared with the W attribute.
You cannot control where in a named memory range a section is allocated, although the linker uses lower memory addresses first and avoids fragmentation when possible. In the preceding examples, assuming no conflicting assignments exist, the .text section starts at address 0. If a section must start on a specific address, use binding instead of named memory.