OLink Target Configurations
OLink has several default target configurations, that associate the various data needed for post-processing the linker output together. Each target configuration includes a linker specification file, default definitions for items used but not declared in the specification file, and a reference to a post-processing tool that will take an image linked against the specification file and generate some final binary image, such as a ROM image or an Operating System executable.
Each target configuration is accessible via the /T linker switch. For example:
OLink /T:BIN test.o
invokes the target configuration associated with the name BIN. In the case of BIN the file is linked into three partitions; code, data and stack using the specification file hex.spc; and the results are dumped to a binary file using DLHex.
The remainder of this section will discuss the default target configurations.
Rom-based images
There are several output file formats for generating a rom-based image. However, they all use a common specification file and post-processing tool. This section will briefly touch on the available output formats then touch on the specification file in more detail.
The available output formats in this mode are:
- /T:M1 Motorola srecord file format, 2 byte addresses
- /T:M2 Motorola srecord file format, 3 byte addresses
- /T:M3 Motorola srecord file format, 4 byte addresses
- /T:I1 Intel hex file format, 16 bits
- /T:I2 Intel hex file format, segmented
- /T:I4 Intel hex file format, 32 bits
- /T:BIN Binary file format
The default specification file for these output formats is hex.spc, and the default post-processing tool is dlhex.exe. Hex.spc has 4 independent overlays for code and data. Table 1 lists the overlays, the section names that are recognized in each overlay. It also lists an identifier that can be used with the /D command line switch to the linker to adjust base addresses, and the default base address for each overlay.
| colheader | colheader | colheader | colheader |
|---|---|---|---|
| Overlay | Sections | Base Address Identifier | Base Address |
| RESET | reset | RESETBASE | 0x00000 |
| ROM | code, const, string | CODEBASE | 0x00008 |
| RAM | data, bss | RAMBASE | 0x10000 |
| STACK | stack | STACKBASE (size = STACKSIZE) | 0x20000 ( 0x400) |
Table 1 - Hex.spc details
WIN32 (PE) Images
Several types of WIN32 images may be generated. These include:
- /T:CON32 - console application
- /T:GUI32 - windowing application
- /T:DLL32 - dll application The default specification file for these output formats is pe.spc, and the default post-processing tool is dlpe.exe. PE.spc has two independent overlays for code and data. Table 2 lists the overlays, and the section names that are recognized in each overlay. Table 3 lists the various values supported by pe.spc and dlpe.exe that may be adjusted on the linker command line.
| colheader | colheader |
|---|---|
| Overlay | Sections |
| .text | code, const |
| .data | data, string, bss |
Table 2 - PE.SPC overlays
| colheader | colheader | colheader |
|---|---|---|
| Definition | Meaning | Default |
| FILEALIGN | Object Alignment within an executable file | 0x200 |
| HEAPCOMMIT | Amount of local heap to commit at program start | 0 |
| HEAPSIZE | Size of local heap | 0x100000 |
| IMAGEBASE | Base address for the image (used to resolve DLL Address collisions) | 0x400000 |
| OBJECTALIGN | Object alignment in memory | 0x1000 |
| OSMAJOR | Set the OS Major version | 4 |
| OSMINOR | Set the OS Minor version | 0 |
| STACKCOMMIT | Amount of stack to commit at program start | 0x2000 |
| STACKSIZE | Size of stack for default thread | 0x100000 |
| SUBSYSTEM | Set the subsystem to a specific value | Normally the subsystem is derived from command line switches |
| SUBSYSMAJOR | Set the Subsystem Major Version | 4 |
| SUBSYSMINOR | Set the Subsystem Minor Version | 0 |
Table 3 - PE.SPC adjustable parameters