Solaris Bug #4095849

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

Bug Id: 4095849
Category: kernel
Subcategory: syscall
State: evaluated
Synopsis: time_constant value >6 with PLL in use leads to integer divide zero trap panic
Description: If the time_constant parameter is 7 or higher, and the phase-lock looping model is in use, the system will take a “integer divide zero trap” panic in the clock routine as soon as the time_offset becomes non-zero.

time_constant defaults to 0. The only place it is set is in the ntp_adjtime system call, from the constant element of the timex structure argument.

Work around: Never set the constant element of the timex structure passed to ntp_adjtime to a value larger than 6.

satish.mynam@Eng 1998-04-30

  1. Use Sun’s version of NTP software instead of PD version. This problem is not seen with Sun’s NTP version (which is mostly eqivalent to PD NTP 3.4 plus some Sun’s local functionality futures).

  2. Workaround for the public domain NTP version ONLY: The workaround for public domain NTP version is to disable the KERNEL_PLL from the NTP code. This way the ntp_Adjtime() system call is totally bypassed without sacrificing any of the functionality of NTP. The only hit you might see is the way kernel precision timinig is done without the PLL algorithm in the kernel.

    The easiest way to disable ntp_adjtime option is(without changing any makefiles or other config files) to disable the KERNEL_PLL value in the ./config.h file.

    After doing a ./configure for probing for all the necessary tools(compilers, OS version, libraries), please comment out KERNEL_PLL macro in the ./config.h file. This will disable the KERNEL_PLL part of the source code and the newly obtained xntpd is just similar to the old one but it does not use ntp_adjtime() system call. This prevents it from panicing the kernel.

    /*#define KERNEL_PLL 1*/

    I complied a new xntpd binary this way and it does not have any ntp_adjtime() related stuff.

    Default:

    /net/divya/export/home/mynam/public_domain/ntp/xntp3-5.92/xntpd>strings
xntpd |
grep ntp_adjtime
354:adj_frequency: ntp_adjtime failed: %m
357:loop_config: ntp_adjtime() failed: %m
435:get_kernel_info: ntp_adjtime() failed: %m

    With KERNEL_PLL disabled in config.h file:

    /net/divya/export/home/mynam/public_domain/ntp/xntp3-5.92/xntpd>strings
xntpd.nopll | grep ntp_adjtime
Integrated in releases:
Duplicate of:
Patch id:
See also: 4133517
Summary: If the time_constant parameter is 7 or higher, and the phase-lock looping model is in use, the system will take a “integer divide zero trap” panic in the clock routine as soon as the time_offset becomes non-zero.

time_constant defaults to 0. The only place it is set is in the ntp_adjtime system call, from the constant element of the timex structure argument.