Re: [PATCH] driver-core: devtmpfs - driver core maintained /dev tmpfs

Michael Riepe
2009-05-04T18:55:47Z

Kay Sievers wrote:
> On Mon, May 4, 2009 at 19:54, Michael Riepe
> <michael.riepe@googlemail.com> wrote:
>
>>>The problem is not the missing events, they could be pretty easily
>>>recovered from sysfs with just another special hack to run at bootup -
>>>it's the time it takes to bring up the engine to bootstrap /dev, to
>>>allow us to start any other process which looks for devices. Today,
>>>udev mounts /dev as a tmpfs, and at that point it is obviously empty,
>>>and needs to be filled, and nothing else can reliably run at that
>>>time.
>>
>>And what about mounting /dev from an already populated image? Or, even
>>faster, using the /dev directory of the root fs? That way, the device
>>nodes would be present as soon as / is mounted, without any additional
>>overhead, except the very first time the system boots (in case you
>>choose not to populate /dev with a default set of device nodes in advance).
>
>
> Dynamic device numbers! A static /dev does not work at all for many
> subsystems, not to mention the risk you take by talking to the wrong
> device pointed to, by your incorrect static device nodes. It's not an
> option at all today, and it will get much worse in the future.

Maybe it's just me, but my devices end up being numbered the same after
every reboot. Unless I add or remove devices to/from the system, of course.

Unfortunately, that doesn't mean that it will always stay that way.

--
Michael "Tired" Riepe <michael.riepe@googlemail.com>
X-Tired: Each morning I get up I die a little