In message <Pine.GSO.3.95.980820203749.4807A-100000@jericho>  "Eduardo E. Horvath" wrote:
> 

[...]

> Sounds good?  Well, there are some problems.  Don't quiesce your root disk
> or you can easily hang your machine.  And keeping track of what devices

Make the tool smarter, and keep it running (and pinned) in case you hit the 
bus where the rootdisk lives. 

> are plugged in where on a system of any size is a nightmare, since you
> never know what physical slot your controller number 1 is plugged into.
> Or is it an on-board device?

Thats why I want device ID's which are unique. On a disk it can be the
label or a serial-number if you can read it. This would make the same
device appear always as the same ID (very handy with removable medias too).

> 
> I strongly recommend deciding what you want to do about device naming
> before embarking on dynamic configuration.  It's really annoying when sd3a
> which has your root partition on it suddenly changes and becomes sd2a
> because one of the other disks did not come up.  And Wiring it down in the
> kernel config file is useless because, since it's a fully dynamic kernel,
> none of the devices are in the kernel config file.  

You still have a config-file somewhere, so it is possible to nail it down,
(also on solaris), but there is a need for identifying dynamic devices on
all busses that 'allow' dymanic configuration, (pcmcia,usb,scsi, hot-swap pci,
... ).
Thats why I think we should add a function to devsw for 'extended' device
configuration, which allows the kernel to interogate the device for
a indentification-ID, which should be unique. All other rarely used options
can go there too (we could overload ioctl, but must driver assume that it comes
with a process-context, eg. they can sleep, so it's not a 'clean' solution).

Stefan

> 
> =========================================================================
> Eduardo Horvath				eeh@one-o.com
> 	"I need to find a pithy new quote." -- me
> 

--
Stefan Grefen                                Tandem Computers Europe Inc.
grefen@hprc.tandem.com                       High Performance Research Center
 --- Hacking's just another word for nothing left to kludge. ---