Re: New fast(?)-boot results on ARM

[Robert Schwebel <r.schwebel@pengutronix.de>]

Marco,

On Tue, Aug 18, 2009 at 12:06:48PM +0200, Marco Stornelli wrote:
> Yeah, I agree, do you really need udevd, device file creation at every
> start-up in /dev? Usually static devices nodes and mdev for hotplug are
> enough or at least you could use a simple script to create only once
> time the devices file (mdev -s). About the fs, do you really need a
> rootfs with ubifs? I mean, you could "split" your fs. You could use a
> read-only fs (SquashFS for example) for your root-fs, ubifs for
> permanent storage data (mounted under /data for example) and a ram fs
> for volatile data.

Well, we try to find out what is possible with a fast booting Linux
system which *still* is as "vanilla" as possible.

All the "boot-in-one-second" systems out there are highly squeezed,
which is surely good if you have a scenario with high production
volumes. You can do the optimization in the last steps then and it
doesn't really matter how much time you spend with testing to come from
a system that works for a developer to a production system.

For most of our use cases here at Pengutronix, we see that:

- Customers want in-system upgradability on a per-packet base; so the
  flash filesystems should be normally r/o, but may be remounted r/w.

- Development systems should be close to production systems, in order to
  be able to have more "early testing"; so things like printk-ripout or
  special non-mainline patches/tweaks should be avoided as far as
  possible.

- In general we want to have our systems close to what the mainline
  does; Automation & Embedded is only a small market, and anything
  which is *not* specific to these markets but mainline is good.

So let's see what we'll reach while trying what people have suggested.

Thanks,
rsc
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