Re: [XenPPC] Xen and firmware RTAS

[Jimi Xenidis <jimix@xxxxxxxxxxxxxx>]

On Dec 6, 2006, at 4:28 PM, Yoder Stuart-B08248 wrote:

> Is Xen/PPC is reliant on any OF/RTAS services being resident.
>
> Doing a quick grep of the code turns up what looks to be
> calls to initialize the rtas, and calls to rtas halt and reboot
> functions.
We instantiate RTAS only for IBM JS2x because there is no public  
specification available on how to perform halt and reboot directly on  
these machines.  For this reason the FW (SLOF) provides us with RTAS  
methods for performing this task.  Newer JS21s will soon have devtree  
entries so we can access the IPMI logic on these boards, when that  
happens we will probably cease to use RTAS for these operations and  
use IPMI.  So really we consider RTAS as a last resort.
> Do you know if Xen relies in any other way on services being
> available by resident firmware?
Xen does _not_ rely on RTAS, but it _can_ use it if it needs to.
Another example where we would have to use RTAS more is if we ported  
to a PPC platform that did not publish the IO host-bridge  
specification but abstracts it using RTAS, in that case we would not  
only use but, but we would actually have to virtualize it as well.
-JX



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