[cgl_discussion] Re: Requirement of Hot Identity

greg k-h greg at kroah.com
Tue Oct 15 09:54:47 PDT 2002

On Tue, 15 Oct 2002 01:30:18 -0700, Yang, Harold wrote:
>>Idea is to ensure that the higher level entities see it as the same
>>device, e.g., if it is /dev/sda6 the first time it's installed, second
>>time it is also /dev/sda6.
> Yes, I got the idea. However, even though it is a requirement of Hot
> Swap support in CGLE, it depends on Linux kernel subsystems to do this
> kind of identity. The naming schema of each subsystem should retain the
> information of devices that had been inserted into the system so that
> when it was inserted again, subsystem can give it a right device name.
> For example, if a network card is hot inserted into the system, it could
> get an interface name of "eth1". When it is hot removed, the network
> subsystem should retain the information of this card (MAC address, etc).
> When it is inserted into the system again, network subsystem will browse
> all retained information and give it a proper interface name (eth1).
> So it seems that although it is a requirement of Hot Swap support, it
> has nothing to do with Hot Swap. It is the business of each kernel
> subsystem. Am I right?

No, it's actually a userspace requirement, and _not_ a kernel issue.
There should not be any naming policies in the kernel.

It's up to the kernel to provide userspace with enough information to do
this kind of naming (like always set a specific MAC address to eth1).
Right now, in the 2.4 kernel some of this is possible (like network
device naming), but for most devices, you will have to use a 2.5 kernel,
combining driverfs with /sbin/hotplug notifications.  See some posts to
the linux-kernel mailing list from both me and Pat Mochel for how this
will be done.


greg k-h

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