AIX Hints

Last update: May 4, 2022 17:05 UTC (dbea9b7d4)

Problem with recent ANSI compilers

On some systems, including AIX, the compiler quits on the ntp_refclock.c file when processing the refclock_report() routine. The problem, which is either a feature or a bug, has to do with an unwanted promotion of the u_char argument to an int and a failure of the compiler to recognize the preceding prototype. A workaround is to use ANSI syntax to delare the arguments. Since ANSI compilers are not universally available, this syntax can’t be used in the stock distribution.

(Message # 60: 2884 bytes, New)
Date: Sat, 19 Aug 1995 13:20:50 -0400
From: "R. Bernstein" Newsgroups: comp.protocols.time.ntp
to: mills@udel.edu
return-receipt-to: rocky@panix.com
Subject: time and AIX 3.2.5 raw tty bug

This posting isn’t strictly about NTP, any program that may stop the clock or set the clock backwards is subject to the AIX 3.2.5 bug.

On AIX 3.2.5, there is a bug in the tty driver for a raw device which may crash the box under certain conditions: basically a read() on a raw tty; in effect, a character was read but not as many as specified by VMIN when a read timeout occurred. VTIME specifies the timeout. See the AIX manual page on termios.h or that include file for information on VMIN (or MIN) VTIME (or TIME).

A remedy other than to not use raw tty’s is to apply patch U435110.

Details of the problem report follow.

---

ABSTRACT:

IX43779: TRAP IN PSX_TIMEO

ORIGINATING DETAILS:

Stacktrace shows:

IAR:      01460214   posixdd:psx_timeo  + 8bf4: ti 4,r12,0x0
*LR:      014601a0   posixdd:psx_timeo  + 8b80
00212c60: 014604f4   posixdd:psx_timer  + 8ed4
00212cc0: 0144b74c   ttydd:tty_do_offlevel  + 4284
00212d20: 000216fc  .i_offlevel + 8c
00212d70: 00021d78  .i_softint + c8
00001004: 00008714  .finish_interrupt + 80

RESPONDER SUMMARY:

AIX asserted in psx_timeo(). Reason for the assert was that the current time was behind psx_ctime. Since this state can occur when the current time is changed after a character is received but before the VTIME interbyte timer pops, we should not assert on this.

RESPONDER CONCLUSION:

Removed the requirement that current time > psx_ctime by adding a new L_ntimersub macro that is used instead of the ntimersub macro in time.h. Also added a test for (current time - psx_ctime) being negative, in that case we do not adjust the new timeout.

Reported to Correct a PTF in Error: NO

Reported as a Highly pervasive problem: NO

PE Apar?: NoPE

Hiper Apar?: NoHiper

Status: CLOSED PER

Component Name: AIX V3 FOR RS/6

Version: 320

Component ID: 575603001

Submitted: 94/05/03

Closed: 94/05/05

ChangeTeam: TX2527

APAR FIXED BY: U431696 U432151 U432844 U432870 U432979 U433049 U433081 U433459 U433876 U433906 U434598 U434453 U434672 U434737 U435110