Plans for hal 0.5.x

Kay Sievers kay.sievers at
Mon Dec 13 08:11:50 PST 2004

On Mon, 2004-12-13 at 10:47 -0500, David Zeuthen wrote:
> On Mon, 2004-12-13 at 16:29 +0100, Kay Sievers wrote:

> > I'm all for keeping the layered architecture and the "low level" clean.
> > We should not touch basic hotplug (what udev is in that case) with D-BUS
> > and friends as there are a lot of good reasons people don't want that.
> > 
> > I serialized the whole event stream for that reason including the
> > physical device:
> >   you get /devices/* -> /block/sda -> /block/sda/sda1
> >
> > It doesn't matter how long each event takes, it will always be this
> > order!
> > 
> > It is the default behavior of udev/udevd, no configure or compile time
> > option, which is nice. If someone has an example, why the simple
> > serialization doesn't work I will try to solve that. Promised! :)
> > 
> Cool, however if we use dev.d to tell hald, won't there be a race
> between multiple copies? E.g. we'd have to reorder in hald
> anyway?

HAL will only need to use _one_ notification program in /etc/hotplug.d/.
Multiple instances are run at the same time, yes. This is intentional,
for performance reasons (think of SMP boxes with a lot of disks).

But hal doen't need to care about that I think, cause every device chain
sequence is still serialized. Only events for independent devices (every
single one is still serialized) may be mixed up:
 /block/sda/sda1 will wait for /block/sda but not for /block/sdb

So you may get /block/sdb before you get /block/sda Do you think that's
a problem and we need to reorder that?


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