Bug 68177

Summary: [HZ=1000] pppd can't call out with kernel > 2.4.18-5.47
Product: [Retired] Red Hat Raw Hide Reporter: Need Real Name <kimiko>
Component: kernelAssignee: Dave Jones <davej>
Status: CLOSED ERRATA QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 1.0CC: pfrields
Target Milestone: ---   
Target Release: ---   
Hardware: i686   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2004-10-26 01:58:03 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Need Real Name 2002-07-07 14:26:51 UTC
Description of Problem:
With kernel rpm versions 2.4.18-5.55 and -5.61, pppd exits after the chat script
fails to establish an outgoing connection.

Version-Release number of selected component (if applicable):
2.4.18-5.55 and 2.4.18-5.61, so far.

How Reproducible:
Every time.

Steps to Reproduce:
1. Install a kernel newer than 2.4.18-5.47 (tried with -5.55 and -5.61) and reboot.
2. Start pppd.

Actual Results:
After the chat script sends ATDT<phone number> to the modem, nothing happens (no
connection, not even a click signifying an opened phone line). After the timeout
period (30 secs), pppd exits.

Expected Results:
After sending the modem the ATDT<phone number> sequence, the modem should after
a while respond with a CONNECT answer and pppd should take over from there,
establishing the ppp0 interface.

Additional Information:
The first two commands sent to the modem ('AT' and 'ATH0') do result in 'OK'
answers.
Adding an extra 'ATH0' command before the 'ATDT' sequence fails to produce the
expected 'OK'.
Minicom has no problem at all communicating with the modem or calling out.

Comment 1 Arjan van de Ven 2002-07-07 18:29:54 UTC
It would be interesting to see if the i586 kernels DO work. If they do, well,
then I know what to look for (just not quite yet where to look)

Comment 2 Need Real Name 2002-07-07 21:38:41 UTC
Yup, kernel-2.4.18-5.61.i586.rpm doesn't have the bug. I'm glad I didn't try
that for nothing (took an hour to download). Now do you know what the problem is?

Comment 3 Arjan van de Ven 2002-07-08 09:01:25 UTC
The i686 kernels have HZ (the internal kernel clock) set to 1000 while the i586
kernels (and the 2.4 kernels form kernel.org) have it set to 100. We do this
because it improves "interactive feel" and it should be fine (in theory ;)
because other architectures have different HZ already (Alpha has 1024 for example).

It seems something in the ppp path doesn't take HZ != 100 into account;
examining....