Re: [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to diskupon panic

[Pavel Machek]

Hi!

> > I think the biggest areas of practical concern would be:
> > 
> >  - Can this mechanism ever, under any circumstance corrupt any real
> >    data, destroy the MBR or do other nasties. Can you think of any
> >    additional fail-safe measures where you could _further robustify
> >    the BIOS calls_ to make sure it can never go to the wrong
> >    sector(s)? I really do not want to think of trusting a BIOS to
> >    _write to my disk_.
> 
> It's quite unlikely but I wouldn't say it's completely impossible.
> It's common for ATA controllers to have dual modes of operation - the
> old IDE compatible interface by emulation which is used by BIOS and
> older operating systems and newer interface (ahci) to be used by
> modern OS.  Some need to be explicitly switched and some just need to
> be accessed carefully.  If the controller is accessed by bIOS after
> switched to ahci or commands are in progress via ahci, anything can
> happen.

Could we read the log area, first, verify it contains signature, write
it back?
								Pavel
-- 
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