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Re: Bug#345067: My understanding of the IDE mess, and why it does not make sense to apply the proposed patch

On Thu, Mar 09, 2006 at 08:08:04PM -0800, Steve Langasek wrote:
> On Thu, Mar 09, 2006 at 11:08:33AM +0100, Sven Luther wrote:
> > Steve, what is the interest of doing this ? We only have 2.6.15 currently in
> > sid/etch, and sarge uses 2.6.8 together with initrd-tool, so it is a
> > non-issue.
> Whether this workaround is needed for older kernels is a technical factor.
> You may not consider supporting older kernels worthwhile (and neither do
> I in this case, really), but it's clear that Jonas *does* consider it

Yeah, the main problem, is that, at least under my impression, jonas, followed
to a lesser degree with Manoj and kernel-package, do believe that self-built
kernels are (much) more important than official kernel ones, which i believe
is a problem the kernel team and also the release managers will have to deal
with. And maybe the technical comittee could give some guidelines there.

> important; if he didn't, there would obviously be no need to overrule
> Jonas at this point.  Since he does, it's important that we have as much
> information as possible about this case in order to make an informed
> decision.  Reaching a technical solution that satisfies both parties
> should *always* be preferred over forcing a maintainer to do something
> he disagrees with.  But even if that's not possible, we still have a
> responsibility to base our decision on as clear a picture of the
> evidence as possible.

Well, it is my point that if there was such a bug, and there may be one
indeed, it is necessary to fix it in the kernel, and not do some workaround in
the tools. Failing to do this research has made us delay the understanding of
this problem since november or so, which i believe has been painful to

The correct solution for the tools who wish to support older and known broken
kernels is probably not to do some hacky and half understood workaround, but
to document the issue in an errata document, and let the user live with the

> I've done a little poking of my own at sysfs based on the comments in
> the yaird code.  I can confirm that it is possible for a PCI IDE driver
> to be listed as associated with a PCI device without actually being the
> driver used to access the device.  This happens on my alpha, where
> ide-generic must be used due to bugs in the cmd64x driver, yet running 
> modprobe cmd64x does show this driver associated with the PCI device:
> $ ls -l /sys/devices/pci0000\:00/0000\:00\:0b.0/driver
> lrwxrwxrwx 1 root root 0 2006-03-09 19:46 /sys/devices/pci0000:00/0000:00:0b.0/driver -> ../../../bus/pci/drivers/CMD64x_IDE

Mmm. When this was happening, could you use and mount partition on this device ? 
And when doing so, do you know which of ide-generic or cmd64x would be used to
read the drive ?

And again, is the right thing to do here, not to fix those cmd64x bugs ? 

> However, /sys/block/hda/device still points to the right place, and it's my
> understanding that /sys/block is what yaird walks, so this still is no
> explanation for how someone could have mis-identified a bug in this area.

How does it find the device and then the driver starting from block ?


Sven Luther

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