Built-in modules review

[Tim Gardner]

On 03/16/2010 09:08 AM, Andy Whitcroft wrote:
> During the karmic cycle we built-in a number of modules.  Some as part
> of the removal of udev random module loading, and some as a part of
> trying to speed up the boot.  At that time modprobe was significantly
> slower than it is now and it is appropriate to review that decision.
>
> We have also had a number of problems reported wherein people can no
> longer parameterise their modules as they wish and/or replace them
> easily to test updated features.  In one specific case the wrong PATA
> driver is binding to the device and as it is built-in there is no longer
> a remedy.
>
> I have prepared a summary of the sub-systems and drivers as built-in
> currently and added them to the blueprint kernel-lucid-config-review's
> spec, at the URL below:
>
>      http://tinyurl.com/ygvwbks
>
> Filesystems: we currently have all of the ext2,3,4 filesystems builtin,
> plus all of the diagnostics filesystems (procfs et al), and also fuse.
> Other than FUSE these are all boot essential.  I believe FUSE is
> required for automounting which needs confirmation.  No changes
> required.
>
> Subsystems: of those listed the only one which appears to be a
> candidate for modularising is netfilter, I cannot recall this being
> required builtin.
>

While not required, its unlikely to have an impact either way. The 
netfilter core has no module parameters. All of the filter extensions 
are already build as modules.

> Network Protocols: again these seem reasonable, the only candidates for
> review being DCB and XFRM, if anyone can confirm that we need those.
>

Wasn't 'boot essential' one of the requirements for being built-in? I've 
never encountered these protocols in real life.


> ATA Drivers: we have the majority of the PATA and SATA drivers built in.
> We already have reported issues with the PATA drivers where blacklisting
> could be used as a work around if they were not built in.  We are also
> exposing users to some level of risk including all these drivers which
> are not used.  In testing on the reference platform I did see a minor
> but measurable performance hit to modularising the SATA driver there.
> As we are moving to SATA over time I would propose we pull out all of
> the PATA drivers and build in only the 2 or 3 most common SATA drivers.
>

Agreed.

> Input drivers: here most things are modules already.  TOUCHSCREEN and
> TABLET are possible candidates for modularising.
>
> HID drivers: we already took action to move HID to modules and most of
> the actual drivers already appear to be modules.  No changes required.
>
> If people are in agreement I will put together a patch set to make these
> changes.
>
> Comments?
>
> -apw
>


-- 
Tim Gardner tim.gardner at canonical.com