Re: [DistroKit] [PATCH v3 1/4] x86_64: kernel: update config

[Michael Olbrich <m.olbrich@pengutronix.de>]

On Tue, May 05, 2026 at 01:33:56PM +0200, Ahmad Fatoum wrote:
> On 5/5/26 1:17 PM, Lucas Stach wrote:
> >  CONFIG_UTS_NS=y
> > -CONFIG_TIME_NS=y
> > +# CONFIG_TIME_NS is not set
> 
> Just spitballing here: With an eye towards Y2038, do we maybe want to
> keep this enabled?
> 
> - Positive Offset: Enable isolated testing of components with y2038 time
> - Negative Offset: Run proprietary components that were't fixed in the past?

I think this can be enabled when needed. If you try to use it, and it's not
enabled the you will get a failure, so there should be no silent failures.

> > +CONFIG_INITRAMFS_PRESERVE_MTIME=y
> 
> FWIW, I normally disable this as this is just extra work that I don't
> see the need for in my BSPs.
> 
> Quoting 1274aea127b2 ("initramfs: add INITRAMFS_PRESERVE_MTIME Kconfig
> option"):
> 
> """
> This change adds a new INITRAMFS_PRESERVE_MTIME Kconfig option, which
> can be used to disable on-by-default mtime retention and in turn speed
> up initramfs extraction, particularly for cpio archives with large
> directory counts.
> 
> Benchmarks with a one million directory cpio archive extracted 20 times
> demonstrated:
>                                 mean extraction time (s)        std dev
> INITRAMFS_PRESERVE_MTIME=y              3.808                    0.006
> INITRAMFS_PRESERVE_MTIME unset          3.056                    0.004
> """
> 
> Granted my initramfs are probably not big enough to matter, but still
> why do the extra work?

Makes sense to me.

> > -CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y
> > +# CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE is not set
> >  # CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE is not set
> >  # CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE is not set
> > -# CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL is not set
> > +CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL=y
> 
> The thinking so far was that performance gives us the best boot time and
> then we would switch to a more suitable default from userspace.
> 
> Is this outdated practice?

That would require switching at runtime. And a lot of BSP, including
DistroKit, don't actually do it. And in that case defaulting to performance
is a bad idea.
I'd rather have a save default. If someone cares about the extra speedup
then they will actually look at the option anyways and can change it.

Michael

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