On Tue, Jul 11, 2017 at 09:02:11PM +0100, Mark Cave-Ayland wrote: > This will enable the fw_cfg device to be placed anywhere within the QOM tree > regardless of its machine location. > > Note that we also add a comment to document the behaviour that we return NULL > to > indicate failure where either no fw_cfg device or multiple fw_cfg devices are > found. > > Signed-off-by: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk> > --- > hw/nvram/fw_cfg.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c > index 99bdbc2..8ef889a 100644 > --- a/hw/nvram/fw_cfg.c > +++ b/hw/nvram/fw_cfg.c > @@ -1017,7 +1017,12 @@ FWCfgState *fw_cfg_init_mem(hwaddr ctl_addr, hwaddr > data_addr) > > FWCfgState *fw_cfg_find(void) > { > - return FW_CFG(object_resolve_path(FW_CFG_PATH, NULL)); > + /* Returns FWCfgState if only one fw_cfg device type exists. If zero or > + more than one fw_cfg device are found then NULL is returned as per the > + object_resolve_path_type() documentation. This behaviour is correct as > + it ensures that we detect both missing fw_cfg devices and multiple > + fw_cfg devices which could result in unpredictable behaviour. */ > + return FW_CFG(object_resolve_path_type("", TYPE_FW_CFG, NULL)); > }
I believe a one-line "returns NULL unless there is exactly one fw_cfg device" (similar to the one at find_vmgenid_dev()) would suffice. :) -- Eduardo