Re: [Qemu-devel] [PATCH v6 7/7] hw/pci-bridge: format SeaBIOS-compliant OFW device node for PXB

[Michael S. Tsirkin]

On Wed, Jun 17, 2015 at 02:45:05PM +0200, Laszlo Ersek wrote:
> SeaBIOS expects OpenFirmware device paths in the "bootorder" fw_cfg file
> to follow the pattern
> 
>   /address@hidden/address@hidden/...

It's kind of crazy, isn't it?
/address@hidden/address@hidden would make some sense: access rootN through cf8.

But if bios needs to keep this for compatibility, maybe
we have too, to. Kevin?

> 
> for devices that live behind an extra root bus. The extra root bus in
> question is the N'th among the extra root bridges. (In other words, N
> gives the position of the affected extra root bus relative to the other
> extra root buses, in bus_nr order.) N starts at 1, and is formatted in
> hex.
> 
> The "address@hidden" node text is hardcoded in SeaBIOS (see the macro
> FW_PCI_DOMAIN).
> 
> Cc: Kevin O'Connor <address@hidden>
> Cc: Marcel Apfelbaum <address@hidden>
> Cc: Michael S. Tsirkin <address@hidden>
> Signed-off-by: Laszlo Ersek <address@hidden>
> Tested-by: Marcel Apfelbaum <address@hidden>
> Reviewed-by: Marcel Apfelbaum <address@hidden>

This makes this a PC-specific device, which is pretty ugly.
You need to hardcode /address@hidden here, but why not get
/address@hidden from the real root?

> ---
> 
> Notes:
>     v6:
>     - no changes
>     
>     v5:
>     - constify parameter and local variables of pxb_host_ofw_unit_address(),
>       in accord with the previous patch
>     
>     v4:
>     - new in v4
> 
>  hw/pci-bridge/pci_expander_bridge.c | 39 
> ++++++++++++++++++++++++++++++++++++-
>  1 file changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/pci-bridge/pci_expander_bridge.c 
> b/hw/pci-bridge/pci_expander_bridge.c
> index 4398d98..37574ec 100644
> --- a/hw/pci-bridge/pci_expander_bridge.c
> +++ b/hw/pci-bridge/pci_expander_bridge.c
> @@ -42,6 +42,8 @@ typedef struct PXBDev {
>      uint16_t numa_node;
>  } PXBDev;
>  
> +static GList *pxb_dev_list;
> +
>  #define TYPE_PXB_HOST "pxb-host"
>  
>  static int pxb_bus_num(PCIBus *bus)
> @@ -88,12 +90,29 @@ static const char *pxb_host_root_bus_path(PCIHostState 
> *host_bridge,
>      return bus->bus_path;
>  }
>  
> +static char *pxb_host_ofw_unit_address(const SysBusDevice *dev)
> +{
> +    const PCIHostState *host = PCI_HOST_BRIDGE(dev);
> +    const PCIBus *bus;
> +    const PXBDev *pxb;
> +    int position;
> +
> +    bus = host->bus;
> +    pxb = PXB_DEV(bus->parent_dev);
> +    position = g_list_index(pxb_dev_list, pxb);
> +    assert(position >= 0);
> +
> +    return g_strdup_printf("%x/address@hidden", position + 1);

Please document that this reverse order is to match
existing bios behaviour.


> +}
> +
>  static void pxb_host_class_init(ObjectClass *class, void *data)
>  {
>      DeviceClass *dc = DEVICE_CLASS(class);
> +    SysBusDeviceClass *sbc = SYS_BUS_DEVICE_CLASS(class);
>      PCIHostBridgeClass *hc = PCI_HOST_BRIDGE_CLASS(class);
>  
> -    dc->fw_name = "pci";
> +    dc->fw_name = "pci-root";
> +    sbc->explicit_ofw_unit_address = pxb_host_ofw_unit_address;
>      hc->root_bus_path = pxb_host_root_bus_path;
>  }
>  
> @@ -148,6 +167,15 @@ static int pxb_map_irq_fn(PCIDevice *pci_dev, int pin)
>      return pin - PCI_SLOT(pxb->devfn);
>  }
>  
> +static gint pxb_compare(gconstpointer a, gconstpointer b)
> +{
> +    const PXBDev *pxb_a = a, *pxb_b = b;
> +
> +    return pxb_a->bus_nr < pxb_b->bus_nr ? -1 :
> +           pxb_a->bus_nr > pxb_b->bus_nr ?  1 :
> +           0;
> +}
> +
>  static int pxb_dev_initfn(PCIDevice *dev)
>  {
>      PXBDev *pxb = PXB_DEV(dev);
> @@ -191,9 +219,17 @@ static int pxb_dev_initfn(PCIDevice *dev)
>                                 PCI_STATUS_66MHZ | PCI_STATUS_FAST_BACK);
>      pci_config_set_class(dev->config, PCI_CLASS_BRIDGE_HOST);
>  
> +    pxb_dev_list = g_list_insert_sorted(pxb_dev_list, pxb, pxb_compare);
>      return 0;
>  }
>  
> +static void pxb_dev_exitfn(PCIDevice *pci_dev)
> +{
> +    PXBDev *pxb = PXB_DEV(pci_dev);
> +
> +    pxb_dev_list = g_list_remove(pxb_dev_list, pxb);
> +}
> +
>  static Property pxb_dev_properties[] = {
>      /* Note: 0 is not a legal a PXB bus number. */
>      DEFINE_PROP_UINT8("bus_nr", PXBDev, bus_nr, 0),
> @@ -207,6 +243,7 @@ static void pxb_dev_class_init(ObjectClass *klass, void 
> *data)
>      PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
>  
>      k->init = pxb_dev_initfn;
> +    k->exit = pxb_dev_exitfn;
>      k->vendor_id = PCI_VENDOR_ID_REDHAT;
>      k->device_id = PCI_DEVICE_ID_REDHAT_PXB;
>      k->class_id = PCI_CLASS_BRIDGE_HOST;
> -- 
> 1.8.3.1