Re: Question about hotplugging NIC devices to an empty pci-bridge

["Zhoujian (jay)" <jianjay.zhou@huawei.com>]

I've tried to set PcdPciBusHotplugDeviceSupport to be true in MdeModulePkg.dec like below:
gEfiMdeModulePkgTokenSpaceGuid.PcdPciBusHotplugDeviceSupport|TRUE|BOOLEAN|0x0001003d
But the problem still exists. Is there any steps I missed? Or some infos need to populate to OVMF by Qemu?

Could you give me more infos?

Thanks,
Jay Zhou

> -----Original Message-----
> From: Yao, Jiewen [mailto:jiewen.yao@intel.com]
> Sent: Thursday, December 20, 2018 8:09 PM
> To: Zhoujian (jay) <jianjay.zhou@huawei.com>; edk2-devel@lists.01.org
> Cc: Huangweidong (C) <weidong.huang@huawei.com>; liujunjie (A)
> <liujunjie23@huawei.com>; wangxin (U) <wangxinxin.wang@huawei.com>; wujing (O)
> <wujing42@huawei.com>; dengkai (A) <dengkai1@huawei.com>
> Subject: RE: Question about hotplugging NIC devices to an empty pci-bridge
> 
> Maybe you can use EFI_PCI_HOT_PLUG_INIT_PROTOCOL to reserve some resource.
> 
> See MdePkg\Include\Protocol\PciHotPlugInit.h
> 
> Thank you
> Yao Jiewen
> 
> > -----Original Message-----
> > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> > Zhoujian (jay)
> > Sent: Thursday, December 20, 2018 7:34 PM
> > To: edk2-devel@lists.01.org
> > Cc: Huangweidong (C) <weidong.huang@huawei.com>; liujunjie (A)
> > <liujunjie23@huawei.com>; wangxin (U) <wangxinxin.wang@huawei.com>;
> > wujing (O) <wujing42@huawei.com>; dengkai (A) <dengkai1@huawei.com>
> > Subject: [edk2] Question about hotplugging NIC devices to an empty
> > pci-bridge
> >
> > Hi all,
> >
> > The issue occurs when I started a virtual machine in UEFI way by
> > libvirt on qemu-kvm platform, the vm is configured with 8 pci-bridges
> > on root bus0. I hotplug a device like virtual nic to an empty
> > pci-bridge which has no device connected. Login the vm, I can see the
> > device by "lspci"", but it didn't show by "ifconfig -a". Dmesg shows like
> below:
> > pci 0000:04:01.0: BAR 0: no space for [mem size 0x00010000 64bit pref]
> > pci
> > 0000:04:01.0: BAR 0: failed to assign [mem size 0x00010000 64bit pref]
> > pci
> > 0000:04:01.0: BAR 3: no space for [mem size 0x00004000 64bit pref] pci
> > 0000:04:01.0: BAR 3: failed to assign [mem size 0x00004000 64bit pref]
> >
> > Reboot the vm, everything turns back to normal and I can see the new
> > hotplugged nic by "ifconfig -a".
> >
> > Use the OVMF compiling from latest edk2 source code, the same problem
> > arises.
> >
> > So, my questions are:
> > 1) the generic PCI bus driver in edk2 does not allocate IO and/or MMIO
> > for a bridge if there is no device behind the bridge that consume that
> > kind of resource?
> > 2) What's the purpose of this strategy?
> > 3) Why don't allocate resource to all bridges like seabios?
> > 4) Is there any switch for me to turn off this constraint so that
> > every pci-bridge including empty ones can be assigned IO and memory window?
> > Otherwise, each time I hotplug a device to empty pci-bridge, a reboot
> > operation should be implemented to use the device?
> >
> > Any help will be appreciated, Thanks!
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