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Re: [Qemu-devel] [PATCH v6 7/7] hw/pci-bridge: format SeaBIOS-compliant


From: Michael S. Tsirkin
Subject: Re: [Qemu-devel] [PATCH v6 7/7] hw/pci-bridge: format SeaBIOS-compliant OFW device node for PXB
Date: Wed, 17 Jun 2015 21:21:00 +0200

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/...
> 
> 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>
> ---
> 
> 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)


So this trick breaks if we ever do have multiple roots, with expanders
under each.


I guess you could go to parent bus, scan child devices of parent and
count TYPE_PXB_DEVICE devices there.


BTW does this work if we have pci bridges under the default root in
addition to PXBs? Does seabios know to skip regular bridges when it's
counting roots?


> @@ -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);
> +}
> +
>  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



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