[SeaBIOS] [PATCH 1/3] Add 'measurement' code to the BIOS

[Kevin O'Connor]

On Thu, May 21, 2015 at 06:09:23PM -0400, Stefan Berger wrote:
> On 05/21/2015 01:40 PM, Kevin O'Connor wrote:
> >On Fri, May 08, 2015 at 01:45:46PM -0400, Stefan Berger wrote:
> >>@@ -733,6 +743,8 @@ do_boot(int seq_nr)
> >>          break;
> >>      }
> >>+    tpm_returned_via_int18h();
> >I don't understand the name returned_via_int18h here as we're calling
> >int18 in this location, not returning from it.
> 
> 
> I did this assuming that we will eventually have to return from int18.

I don't understand - what does it mean to return from int18?

> >>--- a/src/post.c
> >>+++ b/src/post.c
> >>@@ -197,6 +197,9 @@ prepareboot(void)
> >>  void VISIBLE32FLAT
> >>  startBoot(void)
> >>  {
> >>+    tpm_calling_int19h();
> >>+    tpm_add_event_separators();
> >These calls shouldn't be done from startBoot() - the VISIBLE32FLAT
> >flag does something special to note the end of "init" code sections.
> >I think these calls should be folded into tpm_leave_bios().
> 
> It works the way it is. I can move it, though.

I didn't mean to imply moving would change functionality.  Placing the
code in a VISIBLE32FLAT function, however causes more code to be in
the "fixed" code area instead of the "init" code area (as reported in
the "Total size" line during the build).  Using more "fixed" area is
not desireable as it reduces available ram for option roms and other
low-memory consumers.  Moving the calls up into the caller of
startBoot() (or even further up into tpm_leave_bios) is functionally
identical, but has the added benefit of allowing more code to be
placed in the "init" code area instaed of the "fixed" code area.

Thanks.

-Kevin