Kubuntu/Ubuntu does not remove everything from memory at shutdown

Perry pwhite at bluewin.ch
Thu Mar 11 17:32:41 GMT 2010


Le Thursday 11 March 2010 05.53:21 Howard Coles Jr., vous avez écrit (you 
wrote) :
> On Wednesday 10 March 2010 03:48:35 pm Mark Greenwood wrote:
> > Yes that's exactly what I'm suggesting. Those suggesting this is a
> > Windows problem have missed the point and failed to understand the
> > problem. The problem is that Kubuntu does not correctly shut down and
> > clear
> > memory/microcode/ACPI on a warm reboot. If the system has not been
> > properly shut down then it is not the next OS's problem if hardware does
> > not initialise correctly.
> >
> > Mark
> 
> Here's the deal.  The BIOS clears and initializes the hardware to a certain
> point upon boot up, and when the control is handed over to the OS after the
> bootstrap is loaded, it's up to the starting OS to initialize, and load the
> drivers for all detected devices.  Blaming Kubuntu because Windoze doesn't
> load right has got to be the craziest thing I've heard around here in a
>  LONG time.
> 
> Here's a point you don't get as well:  If you're "warm booting", you're by
> nature NOT clearing all the code in all the adapters at the OS level,
>  you're just clearing and writing out the Hard Drive cache, killing all the
>  apps running, and kicking off a quick reboot via ACPI.  It's up to the
>  BIOS of the box, or the next OS startup at that point to reset all cards
>  and memory.  That kind of completely empty RAM and all other add-on cards
>  would be a complete cold boot, right?  Warm booting means I don't take the
>  time to completely clear and shut down the hardware, I just do a "refresh"
>  boot, hence the name "warm".
[snip]

Stuff remains on memory after a warm reboot, whether from M$ or from Kubuntu.

In my setting I could declare this as a security risk or a violation of 
privacy (just kidding, I don't really care, only it wasn't a good presentation 
of Linux for my friends). 
Let me tell you how it goes:

When I cold boot onto Jaunty, it starts with an inferior resolution and the 
right quarter of the screen contains black and white "staircases" at the time 
the password is requested. A few seconds after I give my password the screen 
finally adopts the selected resolution (1920X1080).
On a warm boot I get scrambled portions of my previous screen flashing on this 
right portion, as well as on the bottom of the screen, long enough that some 
text might be read or pictures seen.

So people really paranoid about their privacy or working on highly sensitive 
material should not be contend of just logging out of their session, they 
should power off.

I am not looking for a cure, I switched to Karmic and don't have this problem 
any more.


Cheers		Perry


-- 
BOFH excuse #270: Someone has messed up the kernel pointers



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