Re: Network Stack Budgeting

["Wu, Jiaxin" <jiaxin.wu@intel.com>]

Hi Tom,

One thing I want to highlight is that our design of network stack is not only for the PXE/HTTP boot trigged in BootManager, but also to make sure it's workable once there is any MNP instance configured by upper drivers (ARP/IPv4/IPv6). 

Take ARP/IP as an example, once ARP/IP are started, we need a heartbeat to process any ARP requests, which is required by ARP functionality. In such a case, SNP must be started to make ARP/IP drivers works well. 

Thanks,
Jiaxin

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> Tomas Pilar (tpilar)
> Sent: Friday, January 25, 2019 1:43 AM
> To: Laszlo Ersek <lersek@redhat.com>; edk2-devel@lists.01.org
> Subject: Re: [edk2] Network Stack Budgeting
> 
> 
> 
> On 24/01/2019 16:49, Laszlo Ersek wrote:
> > On 01/24/19 14:25, Tomas Pilar (tpilar) wrote:
> >> Hmm,
> >>
> >> Mnp->Configure() will eventually call MnpStartSnp().
> >>
> >> A grep for Mnp->Configure shows that:
> >> * ArpDxe performs this on DriverBinding.Start()
> >> * Ip6Dxe performs this on DriverBinding.Start()
> >>
> >> Ipv4 and DnsDhcp do this as a part of their Configure() they expose in the
> API.
> > Yes, that makes sense. All of the above drivers are UEFI drivers that
> > follow the UEFI driver model, AIUI. As long as the controller is not
> > connected from BDS, no BindingStart() function should be called in these.
> Ah, but I would expect the BDS to call ConnectController() on the NIC, but I
> would not expect the network stack to be started unless the device is
> actually chosen for PXE booting. In other words, the above protocols should
> follow the example of EFI_DNS4_PROTOCOL that binds against the device
> during BDS but .Configure() is not automatically called by
> DriverBinding.Start().
> 
> .Configure() should be called by the BootManager if networking is actually to
> be done. That in turn will configure Mnp and start Snp.
> 
> Cheers,
> Tom
> 
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