[SeaBIOS] Saving a few bytes across a reboot

Kevin O'Connor kevin at koconnor.net
Tue Jan 9 16:14:35 CET 2018

On Tue, Jan 09, 2018 at 10:00:44AM -0500, Stefan Berger wrote:
> Kevin,
>    is it possible to save a few bytes, a pointer, across a reboot? I have
> tried to do this by allocating a memory chunk in the fsegement and storing
> the pointer there surrounded by 2 'magic' 32 bit values. When trying to find
> the magic values on reboot early in handle_post() it doesn't seem to find
> them anymore. Is there another memory segment where SeaBIOS could store the
> few bytes and find them again?

Didn't you have that implemented with the "Support Physical Presence
Interface Spec" patches you made back in 2015?

Everything in low memory gets wiped out on a reboot.  Any storage
would have to be above 1M (or in a hardware register somewhere).

BTW, can we move this discussion onto one of the mailing lists?


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