Re: [PATCH] tpm: Document UEFI event log quirks

[Jordan Hand]

On 7/5/19 3:26 AM, Jarkko Sakkinen wrote:
> On Wed, 2019-07-03 at 10:08 -0700, Jordan Hand wrote:
> > > +This introduces another problem: nothing guarantees that it is not
> > > +called before the stub gets to run. Thus, it needs to copy the final
> > > +events table preboot size to the custom configuration table so that
> > > +kernel offset it later on.
> >
> > This doesn't really explain what the size will be used for. Matthew's
> > patch description for "tpm: Don't duplicate events from the final event
> > log in the TCG2 log" outlines this well. You could maybe word it
> > differently but I think the information is necessary:
> >
> > "We can avoid this problem by looking at the size of the Final Event Log
> > just before we call ExitBootServices() and exporting this to the main
> > kernel. The kernel can then skip over all events that occured before
> > ExitBootServices() and only append events that were not also logged to
> > the main log."
>
> Not exactly sure what is missing from my paragraph. The way I see it has
> more information as it states what is used at as the vessel for
> exportation (the custom configuration table).
>
> Maybe something like:
>
> "Thus, it nees to save the final events table size at the time to the
> custom configuration table so that the TPM driver can later on skip the
> events generated during the preboot time."
Yes, that sounds more clear to me.

Thanks,
Jordan