tony@jassys.UUCP (Tony Holden) (08/16/89)
Hope someone can help me decide if waht I should do here. We're running a CCI power 6 MP. We've been having problems with the system going down and have been told by CCI that the problem is with no enough clist space. Question. What exactly is clist (I know unix but not that deep). CCI wants us to reboot every 3 days until they fix the problem. Bogus? Thanks in advance. -- Tony Holden tony@jassys egsner!jassys!tony@texbell.swbt.com jassys!tony@attctc.dallas.tx.us,
cpcahil@virtech.UUCP (Conor P. Cahill) (08/17/89)
In article <134@jassys.UUCP>, tony@jassys.UUCP (Tony Holden) writes: > > Question. What exactly is clist (I know unix but not that deep). CCI > wants us to reboot every 3 days until they fix the problem. Bogus? > Clists are used to store things like character i/o for tty's. They are variable length data areas designed for this purpose. I would guess that the CCI kernel has a bug that causes it to loose track of some clists over a period of time, hence the request to reboot every once in a while. This cannot be a big time bug (I'm sure you won't agree :-) because with any moderate amount of tty i/o, you would run out of clists in a very short period of time. I rebooted the 6/32 a few times in my lifetime, and I know it is no fun having to loose the machine for the time of the reboot (which isn't short), but thats alot better than having the system crash in the middle of day 4 just after you modified /etc/passwd or /etc/inittab.
wescott@ncrcae.Columbia.NCR.COM (Mike Wescott) (08/17/89)
In article <1026@virtech.UUCP> cpcahil@virtech.UUCP (Conor P. Cahill) writes: > In article <134@jassys.UUCP>, tony@jassys.UUCP (Tony Holden) writes: > > Question. What exactly is clist (I know unix but not that deep). CCI > > wants us to reboot every 3 days until they fix the problem. Bogus? > [...] I would guess that > the CCI kernel has a bug that causes it to loose track of some clists over > a period of time, hence the request to reboot every once in a while. > This cannot be a big time bug (I'm sure you won't agree :-) because > with any moderate amount of tty i/o, you would run out of clists in a very > short period of time. Actually there is a nasty little bug in SysVr2 clist manipulation code (fixed in SysVr3) in canon() in io/tty.c by which clist blocks can be lost. It is fairly rare since it requires two readers of the tty with ICANON not set. The most common situation in which this occurs is running HDB uucp to dial out on a port that has uugetty running. This may not be the problem with the CCI machine, I'm not familiar with it. I am, however, rather familiar with the bug and kind of fond of it, since it got me sent to England to investigate a customer's complaint. -- -Mike Wescott mike.wescott@ncrcae.Columbia.NCR.COM
woods@cbnewsc.ATT.COM (Warren D. Swan) (08/24/89)
In article <4922@ncrcae.Columbia.NCR.COM> wescott@ncrcae.Columbia.NCR.COM (Mike Wescott) writes: >In article <1026@virtech.UUCP> cpcahil@virtech.UUCP (Conor P. Cahill) writes: >> In article <134@jassys.UUCP>, tony@jassys.UUCP (Tony Holden) writes: >> > Question. What exactly is clist (I know unix but not that deep). CCI >> > wants us to reboot every 3 days until they fix the problem. Bogus? > >Actually there is a nasty little bug in SysVr2 clist manipulation code >(fixed in SysVr3) in canon() in io/tty.c by which clist blocks can be lost. >It is fairly rare since it requires two readers of the tty with ICANON not >set. The most common situation in which this occurs is running HDB uucp to >dial out on a port that has uugetty running. Aaaaaaaaaaaah. A spark of insight. Perhaps this might explain why the system I use regularly (not cbnewsc) occasionally "hangs" (either everyone, or just me, I forget). It's running 5.2.6b (System V release 2 ...). I and the aforementioned bug may be the culprits. I use shl - the shell layer program for terminals that don't have layer capabilities. Since this program does the multiplexing of the input to several shells (outputs), it seems like the subshells would be multiple "readers of the tty with ICANON not set." Furthermore, I've noticed for some time that it only hung when I was using shl, or at least 99% of the time I was using shl (does anyone else use it?). 'Cause I'd have to log back in and kill my processes (including shl itself) left around when it hung. Perhaps fodder for comp.sys5.bugs? Except we need to be sure before we publish such things as fact there yet. Thanks for your explanation. Warren D. Swan (WooDS) Y n n ____ __ You can't tell which way a train AT&T Bell Laboratories -(((((([__]/__] went by looking at the tracks. Naperville, Illinois /o-OOOOO~~ oo att!cblph!woods ##################### FRISCO 1630 Decapod (2-10-0) IRM