#defines for AIX versions & h/w architectures

[jsalter at slo]

>From: Jon Crowcroft <J.Crowcroft at uk.ac.ucl.cs>
>what predefineds (e.g. is cpp called with any by cc)
>exist for writing sensible 
>#ifdef
>to make code conditionally portable over AIX 
>on PS/2, RS6000 and aix370 on a 3090?

For AIX PS/2 (/etc/cc.cfg), AIX/370 (man cc.cfg) and AIX v3.1 6000
(/etc/xlc.cfg), the following define exists across all platforms:

	_AIX


To indicate differences between them, AIX PS/2 defines (/etc/cc.cfg):

	_I386

AIX/370 defines (according to: man cc.cfg):

	u370

and the 6000 defines (/etc/xlc.cfg):

	_IBMR2

Thus, you can tell the different AIX versions apart by the defines.

>(or does some sensible standard system header have a #define...?)

Well, on the 6000 the attempt at satisfying lots of standards has
occured making the header files full of #ifdefs as this has the least
impact on the system.  The common standards required are in the header
file: /usr/include/standards.h

In AIX/PS2, /etc/cc.cfg contains a line for the posix standard which
should help with compilation to that standard.  There are also flags
for ANSI compliance for both the 6000 XL C compiler and AIX/370 (man cc).

(Yes, I know this isn't the answer you were looking for, I just thought
I'd clarify a few things.)

>jon 

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