[Skiboot] [RFC PATCH] plat/qemu: Add BT device

Stewart Smith stewart at linux.vnet.ibm.com
Tue Jan 12 14:52:06 AEDT 2016

Cédric Le Goater <clg at fr.ibm.com> writes:

> On 01/11/2016 11:11 AM, Benjamin Herrenschmidt wrote:
>> On Mon, 2016-01-11 at 10:50 +0100, Cédric Le Goater wrote:
>>> Well, the current BT device in qemu can be configured on the command 
>>> line, it also has a configurable irq number :
>>>         -device ipmi-bmc-sim,id=bmc0 -device isa-ipmi-
>>> bt,bmc=bmc0,irq=10
>>> So, it seems safer to let qemu populate the device tree depending 
>>> on its qom-tree than allow skiboot to hardcode non existing devices.
>> We could also have the powernv platform instanciate BT by default.


> yes. I gave it a try last year and add a hard time to dissociate the BT 
> device from the backend, that can be the simulator or an external BMC. 
> I will spend some more energy to figure out why the QOM layer was 
> complaining.

External BMC emulator (i.e. different QEMU process) is certainly
something we'd want to do - and that'd help the openbmc folks.

> Do we have plans for a FSP simulator ? Anyhow a hardcoded BT should not 
> be a major obstacle.

I certainly have no plans for an FSP simulator.... and I'm not sure it
would be worth the effort, that protocol is kind of a bit crazy on our
side, let alone what we'd have to implement to emulate FSP side of it...

Is there a simple/sane way to have a device there by default but be able
to be disabled if one is so inclined?

Stewart Smith
OPAL Architect, IBM.

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