Re: [uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[BlaisorBlade <blaisorblade_spam@yahoo.it>]

On Thursday 09 September 2004 21:46, Matt Zimmerman wrote:
> On Thu, Sep 09, 2004 at 09:33:35PM +0200, BlaisorBlade wrote:
> > On Thursday 09 September 2004 20:49, Matt Zimmerman wrote:
> > > Yes, I ran into this problem when testing the 2.4.24-3um packages for
> > > Debian. With previous UMLs, hwclock would simply produce an error, and
> > > the process would continue, but with 2.4.24-3um, it seems to hang.  Any
> > > idea why this might be?
> >
> > Not at all - there is a big bug in 2.4.24-3 with modules (any iptables
> > user get crashes), and "rtc" is probably a module; that bug is fixed in
> > 2.4.26-2, which has another critical bug on console I/O fixed in
> > 2.4.26-3, which is safe (apart all the experimental work on humfs and
> > hostfs, which make them break in multiple ways). By the way, I've not
> > heard this with any other distro (on my own I've only a Slack 9.0 root
> > fs), so a look to hwclock could be useful, maybe.
>
> hwclock has caused problems for UML in the past; one of the strange things
> that it does is to try to open an fd for the console, because some
> architectures use that as a means to interface to the hardware clock.
>
> I ran hwclock under strace to find out where the hang was occurring, and
> discovered that it succeeds when running under strace. :-(  Here's the
> output anyway:

> In the course of this test, I also noticed that it is not just hwclock
> which hangs, but the entire UML.  Not even mconsole works after hwclock is
> run.

> UML in Debian has been in bad shape for some time, after the hostfs
> breakage, and then all the reports of hangs in tt mode
> (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=260111), and I would very
> much like to get a stable version in soon.
Well, I might do a proper patch choosing and release a 2.4.26 (or 2.4.27 - 
hope the patch shouldn't change) without any hostfs change and without known 
bugs (at least I hope).

> FWIW, you can find a Debian UML image (which should easily reproduce this
> problem) here:
>
> http://people.debian.org/~mdz/uml/Debian-3.0r2.ext2.bz2
No broadband, sorry. The only fs I downloaded is the root_fs_tomsbrt, i.e. 
1,4Mega wide IIRC.
> > Also, check for Real Time Clock UML option (enabling/disabling - does it
> > makes difference?).
>
> Currently, it is using CONFIG_UML_REAL_TIME_CLOCK=y.  This has not changed
> for some time:
>
> 1.40         (mdz      16-Dec-03): CONFIG_UML_REAL_TIME_CLOCK=y
If you get any difference by disabling it, let me know.

-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729


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