qdev: Regarding lazy ISA bridge creation

qdev: Regarding lazy ISA bridge creation

[Philippe Mathieu-Daudé]

Hi Cédric,

I'm trying to understand the comment you added in commit
3495b6b6101 ("ppc/pnv: add a ISA bus"):

 /* let isa_bus_new() create its own bridge on SysBus otherwise
  * devices specified on the command line won't find the bus and
  * will fail to create.
  */
 isa_bus = isa_bus_new(NULL, &lpc->isa_mem, &lpc->isa_io, &local_err);

Do you have an example so I can reproduce?

Thanks,

Phil.

Re: qdev: Regarding lazy ISA bridge creation

[Cédric Le Goater]

On 3/24/21 12:13 PM, Philippe Mathieu-Daudé wrote:
> Hi Cédric,
> 
> I'm trying to understand the comment you added in commit
> 3495b6b6101 ("ppc/pnv: add a ISA bus"):
> 
>  /* let isa_bus_new() create its own bridge on SysBus otherwise
>   * devices specified on the command line won't find the bus and
>   * will fail to create.
>   */
>  isa_bus = isa_bus_new(NULL, &lpc->isa_mem, &lpc->isa_io, &local_err);
> 
> Do you have an example so I can reproduce?

I think this is related the IPMI BT device when using an external BMC :  

  https://qemu.readthedocs.io/en/latest/system/ppc/powernv.html

You could use an Aspeed machine for the remote end. But you need the 
aspeed-6.0 branch for that because I did not send upstream the iBT model :

  https://github.com/legoater/qemu/commit/4d2d9fe1211a25738ba5429d07a58c981845af92

C.