Re: [PATCH] modules: CONFIG_MODULE_COMPRESS: add hint that userspace support may easily be missing.

Andreas Mohr
2015-06-04T20:09:31Z

Hi,

On Thu, Jun 04, 2015 at 01:19:46PM +1000, Stephen Rothwell wrote:
> Hi Rusty,
> > But disappointing that Debian doesn't configure with it, and there's no
> > easy way to check it. Looks like Ubuntu vivid is the same.
>
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=772628

Crap, that URL now is an implicit strong suggestion
that I didn't do my homework ;)
(it already described large parts
prior to me regurgitating this issue
due to being unaware of this history here).

Thanks to R.Russell for a very nice shortening
and extension of the help text!

Since the issue of .gz vs. .xz redundancy came up
(with people "threatening" to support only one alternative),
I want to mention that
when having to choose one
I'd tend to activating the .xz library dependency:
- while it has higher compression demands,
hardware is getting beefier all the time,
thus it should not matter
(especially vs. the dominantly many decompression runs)
- it's simply the "more modern" and future-proof option,
thus it should be favoured slightly
since the system as a whole
would want to make reasonably quick
development/evolution "forward progress"
rather than sticking to less favourable mechanisms
- .xz has been available for some time already
i.e. the time window of "distro support maturity" is a given
[a counter-point might be that module-init-tools supports .gz only,
but then modern binary setups which chose .xz
would already have been shipped with kmod only]

OK, having said that,
I'm unsure what to think of the Debian package's decision
to not support compression so far
(and that even in times
where kmod does not provide a runtime option yet
to query the actual set of support flags).
>From a library dependency POV it may be attractive to skip compression,
and since Debian usually has a fixed setup
where non-compressed files are a given,
this seems like a valid choice.
It's just that for e.g. these situations:
- people with many custom kernels installed
- space-constrained systems
this is quite a nuisance that is a wee bit too unexpected (/show-stopper) -
took me roughly > 30 minutes to get it researched / resolved.

Thanks,

Andreas