General information about porting software to IRIX

Introduction

IRIX has a long history, and for this reason there is a lot of stuff in headers allowing software from different eras to be built on it. Given that now, in 2019, most porting tends to focus on recent software, this can cause all kinds of headache when trying to figure out how to get all the necessary definitions included. Here we attempt to document some of that to avoid diving into the deep end every time the compiler complains to us about an incomplete type or an implicit declaration.

Where to find what

struct timeval

A bit surprisingly, this is easiest found in <sys/resource.h>

Equivalences

anonymous mmap()

IRIX does not have this. Instead, you can open /dev/zero, establish a private mmap and immediately close /dev/zero. Functionally this should be a close equivalent.

CLOCK_MONOTONIC

This definition is used to set up a clock that has an arbitrary starting point in time and thus is not affected by changing system time - basically a hardware counter unaffected by wall clock time. IRIX has this functionality in <sys/ptimers.h>, it’s called CLOCK_SGI_CYCLE.

Missing stuff

setenv and unsetenv

Yeah, they simply aren’t there. A wrapper is rather trivial to write. Here’s a GPLv3-licensed example of how to do it:

http://www.man7.org/tlpi/code/online/dist/proc/setenv.c.html

b64_ntop and b64_pton

These symbols exist in libc.so but are hidden. If an application needs these, they need to be sourced from elsewhere. A suitable implementation for copypasting into your code can be found in glibc.

Miscellaneous information

_SGIAPI, _ABIAPI etc

There’s an explanation on how these work in <sys/standards.h> comments. Basically - the larger value you assign to _XOPEN_SOURCE, the more modern featureset you will get.