IPR-NIOS Altera, IPR-NIOS Datasheet - Page 185

• Manufacturer Part Number: IPR-NIOS
• Description: IP NIOS II MEGACORE RENEW
• Manufacturer: Altera
• Type: MegaCorer

Specifications of IPR-NIOS

• License: Renewal License
• Lead Free Status / RoHS Status: Not applicable / Not applicable

Chapter 7: Application Binary Interface
Referenced Documents
Referenced Documents
December 2010 Altera Corporation
Linux Conventions
Development Environment
Linux Initialization and Termination Functions
The implementation is responsible for calling DT_INIT(), DT_INIT_ARRAY(),
DT_PREINIT_ARRAY(), DT_FINI(), and DT_FINI_ARRAY().
System Calls
The Linux system call interface relies on the trap instruction with immediate
argument zero. The system call number is passed in register r2. The arguments are
passed in r4, r5, r6, r7, r8, and r9 as necessary. The return value is written in r2 on
success, or a positive error number is written to r2 on failure. A flag indicating
successful completion, to distinguish error values from valid results, is written to r7; 0
indicates syscall success and 1 indicates r2 contains a positive errno value.
Userspace Breakpoints
Userspace breakpoints are accomplished using the trap instruction with immediate
operand 31 (all ones). The OS must distinguish this instruction from a trap 0 system
call and generate a trap signal.
Atomic Operations
The Nios II architecture does not have atomic operations (such as load linked and
store conditional). Atomic operations are emulated using a kernel system call via the
trap instruction. The toolchain provides intrinsic functions which perform the system
call. Applications must use those functions rather than the system call directly.
Atomic operations may be added in a future processor extension.
Processor Requirements
Linux requires that a hardware multiplier be present. The full 64-bit multiplier (mulx
instructions) is not required.
The following symbols are defined:
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This chapter references the following document: the
Nios II Processor Reference Handbook.
__nios2
__nios2__
__NIOS2
__NIOS2__
Programming Model
Nios II Processor Reference Handbook
chapter of the
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