User guide

Nios II IDE Help System
System Library Page (Properties Dialog Box)
You open this properties page by clicking System Library in the left-hand pane of the
Properties dialog box for Nios II system library projects.
This page allows you to configure compiler and linker options that affect how your program
interacts with hardware, such as:
Specifying a device for the stdin, stdout, and stderr channels
Specifying which sections of code belong in which physical memory
Adding and configuring software components, such as an RTOS or file system
This page contains groups of settings related to target hardware, system library contents, and
linker script. The following sections describe each group in detail.
Target Hardware
This section displays the target CPU and SOPC Builder System. These values cannot be
modified. You must make a new Nios II system library project if you wish to change these
values.
System Library Contents
This bottom-left group of settings affects the contents included in the system library. These
settings configure the behavior of the hardware abstraction layer (HAL)
and the system RTOS,
if any.
RTOS—Specifies the operating system to base the system on. The MicroC/OS-II
option configures the system library to use the MicroC/OS-II RTOS. Other RTOS
choices are available from other vendors. none (single threaded) configures the
system library with a single-threaded HAL runtime environment. If an option other
than none (single threaded) is selected, the RTOS Options... button is enabled.
RTOS Options—Displays configuration options that are specific to the selected RTOS.
Consult the RTOS vendor’s documentation regarding these options.
stdout, stderr, stdin —Allow you to associate the C stdout, stderr, and stdin streams
to devices in the SOPC Builder system. You can choose any character mode device for
each stream. Setting unused streams to null might reduce the memory footprint.
System clock timer —Associates the system clock driver with a timer device in the
SOPC Builder system.
Timestamp timer— Associates the timestamp driver to a timer device in the SOPC
Builder system. The Timestamp timer and the Periodic system timer cannot
specify the same physical device.
Max file descriptors —Specifies the maximum number of file descriptors that can be
open simultaneously for accessing character mode devices and file subsystems. The
default is 32. Using a smaller number might reduce the memory footprint. Max file
descriptors is disabled when Lightweight device driver API is on.
Program never exits —When on, exit() is omitted from the system library. This
reduces memory footprint for programs that intentionally never return from main().
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