Re: System hang when trying to enter sleep/standby state

quoted

quoted

I would recommend never, ever doing 'echo 5 > /proc/acpi/sleep', 
especially if you're trying to suspend the system. 

It's not worse than pushing the power button on a normal system
(or hold the power button on an ACPI system).

You're absolutely right. But, most people do those things deliberately, 
and know the consequences. 

Do you think someone becomes root and does an "echo 5 > /proc/acpi/sleep"
by accident? ;-)

Think about how this thread started: $Random User sees his system doesn't
suspend when writing '4' to that file, so he tries every other value.

This is not a random user. This is someone who plays around with his
system while testing beta kernel drivers. 
The random user at this stage doesn't know about acpi at all. The
random user in the future (when acpi comes with Suse or RedHat Linux 
out of the box) will only use the GUIs to suspend and such. So there's
no problem at all, I think.

That's a perfectly valid thing to do, and the kernel has no right to crash
when he does something like that. 

The kernel has the right to do what the specs say. There might be 
systems where this is wanted (which boot from read only medium and
need a really fast poweroff).

Which is possible, but ludicrous. If you want to halt your system, use
halt(1). We do not need to invent new ways to do old things, especially 
when they are dangerous. 

This is a new thing: You can power off in less than a second.

quoted

The regular user can't write anything to that file - this must be
root. He's supposed to know what he's doing. If he wants to turn the
machine off without halting the system, then that's his choice. Think
of something like an embedded system to control a machine. Many 
machines have an emergency off whith a huge red button. This is the
software version of this red button. Your software can press this
if you thing that's necessary.

That's crap. 

You're too kind.

For one, most systems are single-user systems. 

Do you want a kernel for most systems or a general purpose, scalable
OS? You're thinking the windows way. I'm glad that Linux is better.

That was 
certainly the case for the guy that crashed his system by writing to that 
file. So, by definition, root knows only as much as the most knowledgable 
user. 

No, by definition root is the administrator and knows what he's doing.
It might be true that there are many people out there who do not know
what they are doing - but they hardly ever become root in the console
and echo numbers anywhere in /proc. And if they do so - well, that's
their fault. 

For another, as mentioned before, we have safe mechanisms for halting a 
system. See 'man 1 halt'. 

You have *no* other mechanism to turn your box off in less than one
second.

quoted

I'd like to have it in. I don't know what I could ever use it for,
but I'd really prefer to have this possibility.

Listen to yourself. Also, take into account your design philosophies 
concerning Linux and other operating systems. This comment is poorly 
thought out and completely invalid.

Will you just keep on saying my comment was no good or could you
maybe tell me what exactly is wrong with it?

We don't keep features around because they might be useful to someone at 
some point in the future. We do what is necessary and nothing more. 

Oh, do we? We don't even know what people are doing. This is not a
set top box. This is an operating system. People build all kinds of
stuff from this. Do you think you know what is necessary for *all*
the things that can be done with Linux?

We also don't leave gaping holes for users to accidentally screw 
themselves. Deliberately, sure. But, not on accident, that's just rude. 

Oops, I typed "sudo echo 5 > /proc/acpi/sleep" by accident again.
Sometimes it just happens. ;-)


Jens

-- 
Jens Haug
IKFF Universität Stuttgart              Tel. 0711/685-6422
Pfaffenwaldring 9                       Fax  0711/685-6356
70550 Stuttgart	                haug-X6ztD3ggwzuBAmxm6OvjtTjhTm2NLCe8@public.gmane.org



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