ppc/pnv: Create BMC devices only when defaults are enabled

Commit e2392d4395dd ("ppc/pnv: Create BMC devices at machine init")
introduced default BMC devices which can be a problem when the same
devices are defined on the command line with :

  -device ipmi-bmc-sim,id=bmc0 -device isa-ipmi-bt,bmc=bmc0,irq=10

QEMU fails with :

  qemu-system-ppc64: error creating device tree: node: FDT_ERR_EXISTS

Use defaults_enabled() when creating the default BMC devices to let
the user provide its own BMC devices using '-nodefaults'. If no BMC
device are provided, output a warning but let QEMU run as this is a
supported configuration. However, when multiple BMC devices are
defined, stop QEMU with a clear error as the results are unexpected.

Fixes: e2392d4395dd ("ppc/pnv: Create BMC devices at machine init")
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20200404153655.166834-1-clg@kaod.org>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h
index fb4d0c0234..d4b0b0e2ff 100644
--- a/include/hw/ppc/pnv.h
+++ b/include/hw/ppc/pnv.h
@@ -241,6 +241,8 @@ struct PnvMachineState {
 void pnv_dt_bmc_sensors(IPMIBmc *bmc, void *fdt);
 void pnv_bmc_powerdown(IPMIBmc *bmc);
 IPMIBmc *pnv_bmc_create(PnvPnor *pnor);
+IPMIBmc *pnv_bmc_find(Error **errp);
+void pnv_bmc_set_pnor(IPMIBmc *bmc, PnvPnor *pnor);
 
 /*
  * POWER8 MMIO base addresses