[coreboot] Returning control to v3 from the payload

[Carl-Daniel Hailfinger]

On 14.03.2008 19:51, Peter Stuge wrote:
> On Fri, Mar 14, 2008 at 08:32:05AM -0600, Jordan Crouse wrote:
>   
>> Somewhere in the back of my mind, I think I recall it was a design
>> goal that we support returning control back to v3 from the payload
>> and loading an alternate payload or panicing sanely.
>>     
>
> Hm. I think I recall discussion about multiple "payloads" in a lar.
>   

Indeed. However, that was a while ago and I have no idea whether the
project died. IIRC Uwe or another GSoC student was active in that direction.


>> Is this still a legitimate goal for v3?
>>     
>
> I am very hesitant.
>
> As was hinted to, it's not possible to guarantee all state so best
> not try. With returning comes administration, I much prefer going
> for the strictly linear execution flow.
>   

As a bare minimum to support returning payloads, we'd have to verify
that contents of the stack and other coreboot-generated memory (like
e820 tables) are still OK. Not something I'd like to do. However, if one
"master" payload takes care of all that stuff, I'm fine. Then again,
that would put the master payload in the position to handle returning
slave payloads.

> The way I could like it is if it's all done by a separate payload,
> that sets up an environment and can run many other programs.
>
> I don't like coreboot doing it.
>
> Think kernel vs /sbin/init
>   

Agreed.

Regards,
Carl-Daniel

-- 
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