Linker Tasks

Using Linker commands

•When linking with other libraries (to create an executable), it ensures that the library will use the local definition of a routine rather than a definition that occurs earlier in the link order.

Exporting a symbol is necessary if the symbol must be accessible outside the shared library. But remember that, by default, most symbols are global definitions anyway, so it is seldom necessary to explicitly export symbols. In C, all functions and global variables that are not explicitly declared as static have global definitions, while static functions and variables have local definitions. In FORTRAN, global definitions are generated for all subroutines, functions, and initialized common blocks.

When using +e, be sure to export any data symbols defined in the shared library that will be used by another shared library or the program, even if these other files have definitions of the data symbols. Otherwise, your shared library will use its own private copy of the global data, and another library or the program file will not see any change.

One example of a data symbol that should almost always be exported from a shared library is errno. errno is defined in every shared library and program; if this definition is hidden, the value of errno will not be shared outside of the library.

Hiding Symbols When Combining .o Files with the -r Option

The -roption combines multiple .o files, creating a single .o file. The reasons for hiding symbols in a .o file are the same as the reasons listed above for shared libraries. However, a performance improvement will occur only if the resulting .o file is later linked into a shared library.

Hiding and Exporting Symbols When Creating an a.out File

By default, the linker exports all of a program's global definitions that are imported by shared libraries specified on the linker command line. For example, given the following linker command, all global symbols in crt0.o and prog.o that are referenced by libm or libc are automatically exported:

$ ld /usr/ccs/lib/crt0.o prog.o -lm -lc

With libraries that are explicitly loaded with shl_load, this behavior may not always be sufficient because the linker does not search explicitly loaded libraries (they aren't even present on the command line). You can work around this using the -Eor +e linker option.

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Kenwood HP 9000 manual Hiding Symbols When Combining .o Files with the -r Option
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HP 9000 specifications

The Kenwood HP 9000 is a cutting-edge home appliance designed for culinary enthusiasts seeking to elevate their cooking experience. This powerful kitchen machine stands out for its multi-functionality, combining the roles of a food processor, blender, and mixer into one sleek unit.

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The HP 9000 comes equipped with a variety of attachments that enhance its versatility. Among these are a stainless-steel mixing bowl, a dough hook, a whisk, and multiple cutting blades. This extensive array of accessories means that users can whip up delightful pastries, create homemade pasta, or prepare smoothies with minimal hassle. Each attachment is designed for easy attachment and removal, making the transition between tasks seamless and efficient.

Another key characteristic of the Kenwood HP 9000 is its advanced safety features. The design incorporates mechanisms that prevent the machine from operating unless all components are securely in place. This not only gives users peace of mind while cooking but also ensures longevity for the appliance, reducing the risk of wear and tear over time.

In terms of design, the HP 9000 is both modern and aesthetically pleasing. Its ergonomic shape and compact size make it easy to store and use in various kitchen settings, while the high-quality materials used in its construction guarantee durability and longevity. The user interface is intuitive, with clearly labeled buttons that facilitate operation, ensuring that even novice cooks can navigate the machine effortlessly.

Additionally, the Kenwood HP 9000 features innovative technologies, such as an integrated digital timer and a pulse function for added control during food preparation. These features enhance cooking precision, allowing users to achieve consistent results every time.

In summary, the Kenwood HP 9000 is an exceptional kitchen appliance that combines power, versatility, and safety. With its advanced features and user-friendly design, it is an ideal choice for anyone looking to simplify their cooking process while achieving professional-level results. Whether you're whipping up a quick meal or tackling an elaborate recipe, the HP 9000 is a reliable companion that will inspire culinary creativity.
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