Errors when building a kernel

Oliver Grawert ogra at
Sat Aug 22 12:10:01 UTC 2015


Am Samstag, den 22.08.2015, 13:21 +0200 schrieb Ralf Mardorf:

> Perhaps you understand an analogy. Doing it that way would be like
> measuring with a meter, that is powered by the same current source as
> the circuit you'll measure. IOW I quasi try to archive "galvanic
> isolation" from Ubuntu configs and Ubuntu/Debian rules, to build a
> kernel for Ubuntu. This usually doesn't cause issues, neither for
> vanilla, nor for vanilla rt patched kernels, from Now it
> does cause an issue and I ask for help to do it that way. I know how to
> do it in other ways. Perhaps you understand the "galvanic isolation"
> analogy.
let me answer with an analogy then ... say you want to measure security
aspects of a set of tires on a specific car (grip, temperature etc).

to compare these tires against another set, would you trust the values
you get when you replace the brakes and engine of said car at the same
time you replace the tires for your measurement or would you rather use
the same car unmodified and only put on different rubber ?

if you change all aspects at the same time you are effectively measuring
two sets of tires on two different cars, the data you collect doesn't
really tell anything about the quality of the tires in the end (except
that you know they behave different on different cars).

robie pointed you to a PPA that has mainline debs, did you check if your
drives wake up when running these ? that would be a very simple thing to
test even without the effort of building anything at all and could
easily already point out if an ubuntu config or patch are at fault here.
It would give you a very valuable data point to start from with your
research and narrow down the possible aspects to inspect further.

also note that an ubuntu kernel package is more than vmlinuz and
modules ... there are configs and postinst scripts run at install time
of the deb. given that make-kpkg is a debian tool that nobody in ubuntu
uses for building kernel packages I wouldn't expect the resulting
package to apply the right postinst/preinst config at all for example or
set up /etc/kernel in the same way as an ubuntu built kernel package
does ... sure, you might be lucky and the setup might be the same (I
have no idea if anyone from the kernel team ever looked at make-kpkg
settings to syncronize them with an actual ubuntu kernel package build),
but why risk that if you can easily reduce the possible differences by
just using the right tree in the documented way.


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