Re: [Qemu-devel] [PATCH 1/2 v2] pci: change default value of rom_bar to 2

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Feb 19, 2014 at 03:20:54PM -0500, Bandan Das wrote:
> The following patch depends on the value of rom_bar to
> determine rom blacklist behavior. Existing code shouldn't
> be affected by changing the default value of rom_bar since
> all relevant decisions only rely on whether rom_bar is zero
> or non-zero.
> 
> Signed-off-by: Bandan Das <bsd@redhat.com>
> ---
>  hw/pci/pci.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 4e0701d..12c3e27 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -53,7 +53,12 @@ static void pci_bus_finalize(Object *obj);
>  static Property pci_props[] = {
>      DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
>      DEFINE_PROP_STRING("romfile", PCIDevice, romfile),
> -    DEFINE_PROP_UINT32("rombar",  PCIDevice, rom_bar, 1),
> +    /*
> +     * 0 = disable
> +     * 1 = user requested on, force loading even if rom blacklisted
> +     * 2 = enabled but disables loading of blacklisted roms (default)
> +     */
> +    DEFINE_PROP_UINT32("rombar",  PCIDevice, rom_bar, 2),

How do users figure out this interface?
Read code?
Could we add a bit property rombarforce=on/off instead?
Seems better.

Maybe we should teach bool type visitors
about 0 and 1 being legal values
(call out to int visitor, then check value 0 or 1),
then rombar can be changed to bit property too.

Also, this will need QMP support right?
IIUC rombar is not exposed in QMP ATM.

>      DEFINE_PROP_BIT("multifunction", PCIDevice, cap_present,
>                      QEMU_PCI_CAP_MULTIFUNCTION_BITNR, false),
>      DEFINE_PROP_BIT("command_serr_enable", PCIDevice, cap_present,
> -- 
> 1.8.3.1