[SeaBIOS] varlow/extrastack vs code

Kevin O'Connor kevin at koconnor.net
Mon Jan 23 16:49:00 CET 2017

On Mon, Jan 23, 2017 at 11:11:02AM +0100, Laszlo Ersek wrote:
> On 01/20/17 20:39, Dr. David Alan Gilbert wrote:
> > * Kevin O'Connor (kevin at koconnor.net) wrote:
> >> On Fri, Jan 20, 2017 at 06:40:44PM +0000, Dr. David Alan Gilbert wrote:
> >>> Hi,
> >>>   I turned the debug level up to 4 on our smaller (128k) ROM downstream
> >>> build and seem to have hit a case where it's been layed out so that the
> >>> 'ExtraStack' is at the same location as some code (display_uuid) which
> >>> was causing some very random behaviour;
> Would this be consistent with a stack overflow?
> See commit 46b82624c95b951e8825fab117d9352faeae0ec8. Perhaps
> BUILD_EXTRA_STACK_SIZE (2KB) is too small now?

The ExtraStack isn't used at the point Dave reports the problem -
display_uuid() is part of the init phase and that happens on the main
"post" stack.

> (This is based off 1.9.1)

I missed that earlier - there were some important fixes post 1.9.1 wrt
reboots.  Commits b837e68d / a48f602c2 could explain the issue.  I'd
make sure the issue is still present on the latest version.


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