Re: udevsynthesize as a udevstart+coldplug replacement

[Kay Sievers <kay.sievers@vrfy.org>]

On Tue, Aug 23, 2005 at 10:46:43PM +0300, Mika Penttilä wrote:
> Kay Sievers wrote:
> 
> >Here is "udevsynthesize" a possible replacement for the udevstart/coldplug
> >combination we currently have. Usually very early in the boot process, it
> >gets all available devices from sysfs and synthesizes the events these
> >devices would have generated at creation time.
> >The events are directly passed to the udevd daemom socket. udevd does all 
> >the
> >work and runs all the events asynchronously. udevsynthesize itself does
> >not read any udev rule.
> >
> >It scans block and class devices to create the the device nodes for already
> >available devices, which obsoletes the run of udevstart.
> >After that, it scans for bus devices, which events may load modules or
> >configure the device. If the bus type is known, the usual bus-specific
> >values are added to the event environment.
> >
> >With the "rules-in-daemon" patch, the whole udevstart/coldplug handling
> >(700 events) takes less than a second CPU time on a 1.7Ghz laptop.
> >
> >A typical boot script would do:
> > prepare tmpfs on /dev
> > create /dev/null
> > start /sbin/udevd
> > disable /proc/sys/kernel/hotplug (the input layer is still broken and 
> > needs a kernel patch)
> > run /sbin/udevsynthesize

> What if udevd receives netlink messages and goes into "ignore unix 
> socket" mode before/while synthesize?

No such mode exists. :) Only events with a SEQNUM set will possibly be
ignored if received from userspace after netlink activity is detected.

Kay


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