Re: Can't change partition table anymore

On Wednesday, 6th April 2005, "Poul-Henning Kamp" wrote:

>We will not by default allow people, be it novice or selfdescribed
>wizards, to write to disk sectors which a filesystem is currently
>in possesion of, without a deliberate disabling of the protection
>mechanism.

As a "self described wizard", I know which sectors I can write safely.
Protect the novices all you like, but don't prevent me from doing
interesting/extraordinary things.

>Enabling foot-shooting is in the category of open-heart surgery:
>it is not something we want people to try "just to see if that
>happens to solve my problem".
>
>So the sysctl knob is here to stay, one way or another.

OK, if you want it that way, then make it a feature, not a debug flag.

>It is far less obvious where the documentation of features like
>this belong than most people think.  This is not something that
>belongs in the dd(1) or ata(4) manual pages, although they could
>and probably should cross-reference it.

In the geom man page, perhaps?  (With the cross-references too, of course.)

>It has been suggested that the kernel issue a printf when this
>happens, but that is 100% precisely the wrong response:  that would
>introduce an effective DoS against any machine with a serial console.

I agree that a kernel printf is not a solution.

>And I hate to say this, but this "horribly undocumented sysctl" is
>in company of about 200 other equally undocumented sysctls in the
>system, many of which have equally profound impact on how the system
>works.

Having bad documentation in one area is not a good reason to introduce
poorly documented features in another.

>So for all I care, this discussion is over until somebody comes up
>with a patch we can all agree on.

"Harrumph!" he said, and stalked from the room. :-)

I'm not yet convinced that this whole thing is not just a bug.  I'm off
to read some manuals and some code...

Stephen.