Base Platform linking model
Enables you to create dynamically linkable images that do not have the memory map enforced by the Base Platform Application Binary Interface (BPABI) linking model.
The Base Platform linking model enables you to:
- Create images with a memory map described in a scatter file.
- Have dynamic relocations so the images can be dynamically linked. The dynamic relocations can also target within the same image.
NoteBase Platform is not supported for AArch64 state.
NoteThe BPABI specification places constraints on the memory model that can be violated using scatter-loading. However, because Base Platform is a superset of BPABI, it is possible to create a BPABI conformant image with Base Platform.
To link with the Base Platform model, use the
If you specify this option, the linker acts as if you specified
with the following exceptions:
- Scatter-loading is available with
--scatter. If you do not specify
--scatter, then the standard BPABI memory model scatter file is used.
The following options are available:
The default value of the
--pltgotoption is different to that for
--base_platform, the default is
--bpabithe default is
Each load region containing code might require a Procedure Linkage Table (PLT) section to indirect calls from the load region to functions where the address is not known at static link time. The PLT section for a load region
LRmust be placed in
LRand be accessible at all times to code within
If you do not use a scatter file, the linker can ensure that the PLT section is placed correctly, and contains entries for calls only to imported symbols. If you specify a scatter file, the linker might not be able to find a suitable location to place the PLT.
To ensure calls between relocated load regions use a PLT entry:
- Use the
--pltgot=directoption to turn on PLT generation.
- Use the
--pltgot_opts=crosslroption to add entries in the PLT for calls from and to
RELOCload regions. The linker generates a PLT for each load region so that calls do not have to be extended to reach a distant PLT.
- Use the
Be aware of the following:
- The model by default assumes that shared objects
cannot throw a C++ exception (
- You must use symbol versioning to ensure that all the required symbols are available at load time.
- There are restrictions on the type of scatter files you can use.