Re: dump device

[Andi Kleen]

On Thu, Jun 29, 2000 at 10:20:06PM -0600, [e-mail] wrote:
> At Sequent, we used a 'stand alone dumper'. That is, the OSwould simply
> halt, and return to the bios. The bios would check to see if a valid kernel
> image existed before initializing memory. If it found a valid image, it
> would launch a dumper utility. This allowed us to get good dumps no matter
> how corrupt the operating system had become ( this is a bit of a
> simplification of the acutual process, but it is essentially correct).
> 
> Some vendors have the OS do the dump. I agree that there is some risk here.
> I believe the SGI kernel dump does indeed have the paniccing OS do the
> dump.
> 
> We are unlikely to see a stand alone dumper for linux, as we are unlikely
> to get bios support for such a function on all of the hw that supports
> linux.

(on modern intel:) 

It would be possible to protect the crash dumper from the OS using
System Management Mode on intel (just like BIOS do e.g. for hibernating
on laptops). Unfortunately that quickly becomes very BIOS dependent
and would be probably a nightmare to maintain over a wide range of
common PCs.

Also it does not help against the ``user configured wrong partition table''
error case.

-Andi