[SeaBIOS] Questions on SeaBIOS TPM

Kevin O'Connor kevin at koconnor.net
Fri Nov 20 23:49:37 CET 2015


On Fri, Nov 20, 2015 at 10:31:35PM +0000, Stefan Berger wrote:
> "Kevin O'Connor" <kevin at koconnor.net> wrote on 11/20/2015 12:26:08 PM:
> > Oh, so the code could assume that the tcpa table is not moved nor
> > modified _and_ that the BIOS is also the only writer to the log?
> 
> Unless there is way that the bootloader could give back control to the 
> BIOS, the BIOS would be the only writer to the log.

Well, the bootloader could call HashLogEvent or HashLogExtendEvent via
the 16bit BIOS interface.  Does the code have to worry about a
bootloader (or OS) that manually adds entries to the acpi tcpa table
and then calls one of the HashLogEvent bios functions?  It sounds like
this table is owned by the BIOS and thus the BIOS could fully cache
the last pointer.

-Kevin



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