Likely Duplicate Bugs

Colin Ian King colin.king at canonical.com
Mon Feb 8 15:15:57 GMT 2010


Hi Brian,
On Sun, 2010-02-07 at 18:25 -0800, Brian Murray wrote:
> On Mon, Feb 01, 2010 at 11:56:00AM +0000, Colin Ian King wrote:
> > Hi Brian,
> > 
> > This kernel message are dups of the same BIOS corruption message, but
> > occurs on a wide range of machines. I had a look at the first 15 or so
> > of the dups and saw that there was a wide spread of Aspire, HP Compaqs
> > and Pavilions and quite a number of unknown systems too.
> 
> Should these duplicate bug reports be consolidated into one bug or
> should there be multiple bug reports for each system model?

Well, the warning is the same manifestation of possibly different BIOS
issues from many different BIOSes (possibly even different versions of
the BIOS on the *same* system model), so I'd count these as separate
reports even if there are a lot of them.   I think I would only attempt
to consolidate bug reports based on the same system model or the
"Hardware name" field as reported in the OopsText.txt, e.g.:

Hardware name: HP Compaq nc6120 (PY390ES#ABZ)

..not sure how easy that is to do automatically.
>   
> > Specifically, the kernel fills known regions of the low 64K of memory
> > with a known pattern and periodically monitors them.  Any buggy BIOS
> > that writes to these regions gets detected and the warning is issued.
> > 
> > BIOS corruption of these regions can occur when doing suspend/resume or
> > HDMI cable unplugging.
> > 
> > The error message is a warning - the system's stability is not
> > compromised as the pages being monitored are already reserved for the
> > purpose of being monitored for corruption in the first place.
> > 
> > This check can be disabled by setting the kernel boot parameter
> > memory_corruption_check=0
> > 
> > Since this is intended as a BIOS corruption detection tool perhaps it
> > should be disabled as a compile time option to stop getting these
> > messages. However, it does have some value in showing that the BIOS may
> > be dodgy. 
> 
> Perhaps the ideal solution is to keep it enabled until the final version
> of the release.  This will still provide us with useful information
> about buggy BIOSes but by disabling it for the final release we will
> reduce the quantity of redundant bugs.
> 
Information about buggy BIOSes is useful in one respect, but generally
requires a BIOS fix which means we cannot do much apart from perhaps
recommend a BIOS upgrade - but that's a risky operation which may
provide little or no benefit.

Since the kernel isn't using the memory for anything important then
these kind of warnings are of a small amount of use. However they
possibly give users alarming messages when in fact they are just helpful
for some classes of debugging. Hence they should be totally disabling on
the final release IMHO.

Any comments anyone?

Colin




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