Bug#405870: [Pkg-sysvinit-devel] Bug#405870: sysvinit: halt binary missing ifdown, breaks wake on lan, src...

[Henrique de Moraes Holschuh]

On Sun, 14 Jan 2007, HarryCoin at aol.com wrote:
> problem.   If ifdown isn't being called, I wonder if also sync is not  called?  
> It would explain file system corruption bugs etch / debian folk  have written 
> of across reboots.  

Actually, the lack of a shutdown bus operation on ide, scsi and libata, and
the lack of an automatic cache flush (always) and disk head unload (only
when undergoing system poweroff or a device coldplug unplug operation) when
the bus is shutdown is a rather ugly little misfeature of the *Linux* kernel
(and maybe the others, I wouldn't know).

It has been doing dumb things like this for a long time now.  It was a MAJOR
stupid mistake to ever try to work around this on userspace (userspace
simply does not know enough to get it right always, and it simply *cannot*
do it in suspend-to-disk, and other corner cases), and it will take two or
three years before we manage to fix it and remove the "do it in userspace by
default" crap halt(8) has to carry around.

As for WOL, it looks like we need to stop with the stupid black magic games,
and get an userland-kernel interface that does whatever is right on sleep
and shutdown depending on WOL state, *regardless* of what userspace might
have done to the interface state (up/down).   

If we enable WOL, the KERNEL driver should do whatever it takes to get it to
work on sleep and shutdown.  If we disable WOL, the drive should do whatever
it takes to make sure it will not wake the machine on sleep and shutdown.
Especially since it is clearly device-specific.   And all needs to be done
on .shutdown, and when entering any ACPI sleep, of course.

There is only so much we can do on userspace to fix kernel bugs or
limitations.  The same way that there is only so much the kernel can do to
work around bugs and limitations on userland stuff...

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh