Objective of OpenWRT/x86?

[Joseph Mullally]

On Sat, Apr 29, 2023 at 3:29 AM Elliott Mitchell <ehem+openwrt at m5p.com> wrote:
> I'm looking at the list of built-in drivers and seeing many which
> will perhaps only be used by 25% of installations.

That figure seems hypothetical, but you would propose to break 25% of users
installations for insignificant memory reductions?

>>> Problem is instead of the recommended 128MB memory, 16MB of storage
>>> (https://openwrt.org/supported_devices/432_warning) the virtualization
>>> examples (https://openwrt.org/docs/guide-user/virtualization/start) are
>>> suggesting massively more memory.  256MB (small Xen example), 512MB
>>> (VMware OpenWRT/15.05) or 1GB (Qemu examples).

>> It makes more sense to make a new lightweight VM profile rather than
>> chopping stuff out of the generic ones.
>> But is one needed, and how much memory would be saved? Have you
>> actually tried running the "x86/64" image with 128MB ram under QEMU?
>> Default 22.03.4 install shows 45MB used. With "wpad-openssl" and
>> "kmod-mac80211-hwsim", its up to 53MB. These requirements rise
>> depending on load. I'm guessing those memory figures in the wiki docs
>> are just arbitrary, showing people they can run cool stuff.

> That could be.  Might simply be the wiki needs to have numbers adjusted
> downwards to reflect how much memory a reasonable installation needs
> instead of an advanced doing all the things installation.

This misunderstanding seems to be what drove this discussion and patch
series, along with wanting to cleanup "legacy" functionality others still
use.

Granted, there doesn't seem to be a x86/64 "minimum reqiurements"
requirements in the Wiki which would help clear this up. Probably because
they are so low that people don't really care. The forums also have a few
questions asking about minimum requirements, but the answers are vague.

> As far as creating a slimmed-down VM kernel configuration.  Removing AGP
> support doesn't gain much itself, but then disabling DRM support saves
> 2203648 bytes.  Turning USB support into modules is another 2MB.  I've
> gotten a potentially viable Xen kernel down to 23MB, but I hope to push
> at least somewhat further.

I'm not a developer, but these gains don't seem significant enough to
justify a new virt profile when the current generic x86/64 images will
simply work out of the box.

The only real benefits of a slimmed down virt specific kernel would be a
reduced attack surface (even though the code for undetected devices
should be inactive). But to really commit to that minimal security footprint
would require seperate virt profiles for every VM platform etc. A lot of work
to undertake for a contemplative discussion...

- Joe