Boot charting

On Thu, Nov 17, 2005 at 07:29:38AM +0100, John Nilsson wrote:
> On Wed, 2005-11-16 at 20:31 +0000, Scott James Remnant wrote:
> > I'm currently working on a total rewrite of the hardware detection stuff
> > that should hit the archive within the next 24 hours or so -- I'll mail
> > you when that's in, and get you to try that and the 2.6.15-rc1 kernel
> > and see if that goes away.
> 
> About that. How much hardware detection do you really have to do at boot
> time? It was my impression that initramfs should only do the work
> necessary to get / to mount.

The fun part of this is that / can be anywhere: on an NFS server across a
network, on a USB storage device, on a SCSI or ATA disk, etc.

If you know exactly what you are doing and want to detect only the hardware
needed to mount your current root filesystem as it stands, that can be done
by adjusting the initramfs configuration.

> How much of the detection and module loading scheduling can be done at
> kernel installation time?

The kernel is only installed once, while hardware detection must be repeated
with every boot.

> Would it be possible to have module loading on demand instead?

Not in most cases, no.  For example, USB driver loading (which is among the
slower parts of this process) must take place in order to support USB
keyboards and mice.  There's no way for the system to know whether one of
these devices is attached without performing a scan.

-- 
 - mdz