Cures for 6.4.4 Video Crashes & Snags, Final Edition

[FlameWeasel]

Considering your number of posts,
I thought maybe you thought you weren't welcome.

Well, I thought I'd try replying through a "notification", but the board says you cannot receive them, so I guess I'll write publicly.

I appreciate the thought. It's not exactly that, though, but close. I've used the Knoppix forum on and off for far longer than this account has existed; I don't remember what my previous accounts were here, but I started using Knoppix, and participating here, in early 2004. (Shortly thereafter, I built a new computer and had to switch to Morphix, because Klaus refused to put the "unfree" NVidia video drivers into Knoppix, but still visited here occasionally, and then I moved to a place without internet for a while, and then moved back to civilization, and so on and so forth. You get the idea. Anyway.)

There are two reasons I don't hang around here much. First, because I really have very little to contribute. My technical knowledge of Linux is not high, and the questions here are mostly about Knoppix or Linux configuration. If someone wanted to know about C++ programming or scripting, which were my areas, they probably wouldn't be asking here.

The second reason is, because I almost never get an answer here. Perhaps the forum is simply too dead. Usually, either no one responds, or I get some smart-ass nonsense about "you must prove to us that your computer is flawless, your optical disk was burned perfectly, and that you have recently brushed your teeth before we will condescend to think about the problem that you claim to have experienced but that we do not believe really exists." Why bother, no one is going to answer anyway.

Tonight I fixed a problem that I have asked about, and I believe seen asked, repeatedly. Knoppix has a tendency to blow up the X11 server due to memory leaks. This was why I hated Compiz -- it's so leaky that it causes crashes frequently. When that happens, Knoppix simply kills all the processes and shuts down, with no possibility of recovering data that is on the ramdisk.

It's a stupid design, and if I were dictator, Klaus would be shot for it. Well, ok, maybe thrown into the scorpion pit instead. "Dipl.Ing." my hairy ass, this would be unacceptable from a first-year programming student.

I had managed to track down where the X11 server was started from, and I changed the script so that it was in a forever loop. That usually works -- the X11 server dies horribly, then my loop restarts it. About 80% of the time, I could now save my data.

But sometimes the crash is because cached code pages got corrupted somehow, and when that happens, the X11 server crashes again as soon as it restarts -- an infinite loop of crashes. Other times, I'm not sure what happens, but the machine simply freezes up; it seems like the machine has gone down to a text console in the background, but graphics mode is still set, and nothing works to view the text console. Maybe the keyboard is still in raw mode, or something. I don't know. Nothing that I've tried has worked, not even the so-called "magic sysreq" -- at best, that will sometimes cause the machine to shut down the rest of the way, which is incredibly irritating. I don't want to shut it down, I want to save my unsaved data.

Well, you know what? My laptop still responds to the power button even when everything else has crashed -- it won't actually shut off, I have to rip the battery out of the back to accomplish that, but the disk access light goes on when I push the power button, so SOMETHING still happens.

So, by changing the "powerbtn.sh" script, I came up with a way to save the data. The laptop has a hard drive, and the script now forces all data from the Desktop directory over to a directory on that drive. X11 just crashed about 20 minutes ago on my machine, and so I was able to do a real-world test, and it worked. I have no idea if it will work every time, but at least it's SOMETHING. Tonight, it saved several hours of writing for a class paper due on Monday.

So, I'm back here to post it. Maybe it'll save someone else's data. Maybe Klaus will fix the startx script so that people can save their data manually. Maybe pigs will fly. Most likely, it'll disappear without a trace, but at least I'll have tried.

Thanks again for the Compiz fix. It's extremely useful to me -- I think it's the first time in a few years that I've gotten a useful answer off Knoppix.net. I appreciate it a LOT, and I appreciate your note above.

[utu]

@FlameWeasel

Thanks for the newsy notes.
I hope you will continue to participate and contribute to our forum.

I have turned off the my 'private' option since it has been used by
several in hopes I can solve their unique problems. More than likely
I can't, and the requestor would do better to ask in the open forum,
where others can see and respond to their problem.

If you are a competent scripter, many of us without formal training
can use some tutoring. Please help educate us. As for your needs
in Linux configuration, that's a common thread in which we all are
here looking for answers.

There are a few forum contributors which are too abrasive in their
inter-personal styles for my taste as well as yours. However, they
often have knowledge and/or experience we can learn from if we are
patient enough.

All things considered, I get more out of this forum than any other
I've run across. I do regret we don't have some participation by
Klaus K, himself. I imagine that he is a very popular and busy man
and hasn't the time to devote to this niche.

In keeping with this thread I offer the following update. I've turned
off Compiz, and I've turned back on the lxpanel hide-when-not-in-use.
I occasionally still have a keyboard lock-out that can only be
cured by control-alt-backspace. It only happens when I've also had
LibreOffice in use for spreadsheet operations. I can live with that.
I save my stuff fairly often, so I never lose much, if anything, on
an unplanned shutdown. And, finally, I can't see that the suggestion
in my Post #5 has any effect on any of my complaints whatsoever.

Looking forward to your powerbtn.sh thread.

[Forester]

Hi FlameWeasel,

I too hate questions that are not answered. Not because I ask a lot of questions but because I have many times found that someone has already asked exactly the same question and got no answer.

I decided to do something about that and stop whining that I had nothing to contribute because I'm only an embedded programmer. I decided to try to make sure every thread with a question posted on these forums gets an answer. I did it to see what trying to answer 'bad' questions could teach me about how to ask 'good' questions.

I know this pisses a lot of folk off because it sounds like I know everything. Believe me, I wise enough to know the more I learn the more I know I don't know. Sometimes an interesting question comes along to which I don't know the answer but I can use my experience to find out. I learn stuff, I help people and, if that browns people off sometimes, at least I have an excuse.

Posts by newbies with less than 10 (I think) posts are vetted before appearing on the forums.
This is an anti-spam measure. This entails a delay that is can be such that regulars who monitor "Today's Posts" don't ever see the question. One reason questions don't get answered is they drop down the list.

Forums are for user-to-user help. Most of the folk on this forum are not dead, they are just not geeks. Some questions are asked by folks who clearly know more than anyone else here. They tend not to get answers (that are of any use).

Many questions are asked by people with a Windows background (no offence intended) who are so used to the Microsoft definition of 'intuitive' that they just don't understand enough of what they are doing to phrase their question so that anyone can understand it. They tend not to get answers.

Some questions are actually rants by someone bent on compounding their own stupidity by making it public. For some reason they think everyone, in general, and KK, in particular, are responsible for their inadequacy. They tend not to get answers.

I find myself looking at questions and asking myself does this person merit the effort ? I ask myself does this person seem willing to learn or do they just want their problem to go away ? I ask myself is this person prepared to give (feedback) as well as take or are they just here for what they can get ? You can't tell with first timers, but with people who've been here before, it's a different matter.

Contribution to the forum of voluntary, No one has any right to expect an answer. No one who tries to answer a question has a right to expect feedback but polite feedback really does help.

The worst are the guys with a problem but already know everything and are able to dismiss every suggestion. They don't deserve answers.

On X-11

You seem to know an awful lot about memory leaks in X11 and I will take it that you know what you are taking about. It is a honour to learn from an expert.

If I were to say Windows 7 == SABENA I would mean the whole sorry Operating System. Most newbies might think X Windows or X server refer to the whole desktop experience when you and I know that it is only tiny part.

I am surprised to learn that the X server is (after 30 years still) flaky but the LXDE desktop (still very much 'in development') is not. I'm so glad utu's panel hiding problem isn't an LXDE issue after all.

One of the good things, they say, about Knoppix is it's hardware recognition and support.
It achieves this by using very recent kernels, the latest X server and all the latest drivers possible. Most accept that this may not be as stable at they wish. It seems we should expect better.

You mention nvidia cards. I don't know if you still have one. There is a constant stream of people come on here with a Dell this or a Dell that have video issues. I point them to the release notes on nvidia drivers that none of them have bothered to read. Most are grateful for the tip. They don't find ruling out the obvious before considering the obscure the least bit condescending.

You mention class papers. Perhaps you are a student. Even if you have been using X-11 since before you could walk you would have to be a very mature student to have been using it as long as I have. Your writing does not suggest maturity.

That leaves the possibility that you are some kind of teacher. Perhaps a xenophobe who can't stand the idea the a foreigner could come up with something as clever as Knoppix ?

I've been lucky enough never tp have had memory leak problems with the X server and I've not heard of them. So I learn something. I have had problem with X video drivers and the frustration of data loss that goes with them hanging. Most of the problems I have had have been with proprietary drivers. I avoid them and I will pay good money to not use a ATI/Radeon grahpics card at all under Linux. I know, totally irrational, but once burnt, twice shy.

You sound cross that Knoppix does not include proprietary drivers. You've a hard drive installation so no doubt you installed the proprietary driver yourself ages ago. I thought the main reason for preferring proprietary drivers over the open source ones is they have better support for 3-D acceleration needed for compositing. Yet you are so grateful to utu for telling everyone how to turn off Compiz, the compositing window manager. I learn something from this.

Myself, I have never turned Compiz off (other than out of curiosity). I managed to run Eclipse on a Knoppix machine with only 512 Kb RAM (and, thankfully, lots of swap space), with Firefox, Konsole, Konqueror and Kate at the same time. I never saw any evidence of a memory leak. Mind you this was at work so I never left it running for more than 8 hours at a time.

On Solution Spaces

As a teacher you understand problem spaces and solution spaces and that happiness lies in the intersection. Knoppix may be the Swiss Army Knife of Linux distributions but, heck, to use a Swiss Army Knife well you need to appreciate and respect its limitations.

I'm a programmer and I've been using Knoppix at work to program stuff. Knoppix is not meant for serious stuff like programming so I wouldn't recommend it unless you want to write programs for Knoppix and even them you should not write and test under the same instance of Knoppix. For me Knoppix was the best compromise I could come up with at short notice (and I mean compromise, not trade-off). I recognised and lived within its constraints.

I did not do a HD install. Knoppix is not meant for that. I've read recently that the HD install is only there to allow people to remaster Knoppix without needing to install some other Linux. People use HD install at their own risk. That's not smart arse, its hard nose.

Knoppix, even HD Knoppix, uses persistent store which you know has a higher write back latency that regular file systems. With Knoppix LiveUSB, the persistent store is usually on a FAT file system which is about as robust as a tin shack. To minimise the risk of loosing the lot, I rigged up my USB stick to boot off ext3 partitions.

Even then I only use the persistent store for configuration and stuff. Real stuff, like the programs I can't afford to loose are on another file system outside of the UNIONFS scheme of things and so are as good as with a real Linux HD installation like Debian.

I know shit happens. This way I don't wait until it has happened to do something about it.

On Knoppix Shutdown

A quick:

dpkg -l | fgrep knoppix

shows that KK has contributed two dozen packages, mostly startup/shutdown or configuration scripts, to Knoppix and has altered only three himself. The vast majority of package come direct from the Debian repositories for which KK cannot be held responsible.

I am surprised to learn that KK's alteration of the "artwiz futuristic mouse cursor for x11" makes him responsible for memory leaks in the X server severe enough to give you problems.

Knoppix, as you know, has no display manager: when you exit the X window environment you don't get a new login screen. Knoppix shuts down. This is not a silly assumption in a start-up script but a deliberate design choice by KK and makes perfect sense for a LiveCD. An example of the solution space in which you have chosen to live when you installed to HD.

The shut down sequence of Knoppix flushes all pending disk writes and so should make sure the persistent store is up to date. From what you describe it seems this does not happen. Perhaps this is the price you pay for using a HD installation. Perhaps this is a bug in the Knoppix scripts but here is not the place to report it. KK does not read these forums. He does have a Debian mailing list and I'm sure would be very interested in your observations. Provided you are polite enough not to threaten his life, liberty or libido.

Thank you for the magic sys req reminder. You know all about it, which is amazing: I use it so seldom that I can't remember how to when I need to. I am suprised to learn that REISUB works before X Windows crashes but not after: I had been led to believe the magic sys req was independent of X windows. I shall refrain from making any smart arse suggestions.

Using the Power Button is neat. That's an interrupt and has nothing to do with the keyboard. I would like to try it but the X Windows on my Knoppix LiveUSB stubbornly refuses to crash. Perhaps you could tell us which WP you were using for your class paper ?

Oh, and of course you're welcome here. Bring the attitude and we can all have a good laugh.