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Re: udev event completion order

I demand that Alexander E. Patrakov may or may not have written...

> Kay Sievers wrote:
>> There is also the plan to do parallel device probing inside the kernel
>> some day, that will make the situation of relying on kernel names even
>> more fragile.

> Right, this means that the way of passing "root=/dev/hdc2" will no longer
> work because /dev/hdc will sometimes become /dev/hde.

I'd call that broken, just as I consider udev (076) to be broken given that
it breaks expectations wrt device naming. (Here, it swapped the names of the
DVD drives (drivers are built-in) and sound devices (drivers are modular).)

If the parallel probing is done such that the naming remains predicatable,
that's good. Whether it's faster doesn't matter - userspace isn't affected
and doesn't require modification, and that's a good thing.

> If you are serious about going to implement this, first add (to
> linux-2.6.16?) a boot-time warning if the kernel is booting without
> initramfs. The warning should say something like this:

> WARNING: you have booted the kernel without initramfs and passed an
> explicit root device name.

I see no problem with booting like that. I've always used the root device
name; why should I forced to change should a kernel upgrade become necessary
just because of some should-be-in-2.7.x [1] breakage?

> This will no longer work when the kernel will probe devices in parallel
> (i.e., since linux-2.6.??) because device ordering will be random. Please
> create an initramfs that mounts the root device using some stable
> attribute, like label or UUID.

That'd be "stable and duplicatable", and I fully expect somebody to run into
that sooner or later...

[1] Heated discussion, anybody? ;-)

| Darren Salt | nr. Ashington, | d youmustbejoking,demon,co,uk
| Debian,     | Northumberland | s zap,tartarus,org
| RISC OS     | Toon Army      | @
|   Kill all extremists!

I've got 256K of RAM, so why can't I run Windows 3.1?

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