[ipxe-devel] Using iPXE with UNDI driver

[Lantz, Philip]

> On Friday 01 Jul 2011 19:23:29 Lantz, Philip wrote:
> > > Under EFI, iPXE can either use a built-in iPXE driver (i.e. something
> > > under drivers/net), or use an existing EFI network device via an EFI SNP
> > > interface. Your driver needs to provide an EFI SNP interface, or rely
> > > upon components that consume an EFI UNDI interface and provide an EFI SNP
> > > interface.
> >
> > I suspected this -- thanks for confirming it -- and I have tried loading an
> > SNP interface on top of my UNDI driver before running iPXE, but iPXE still
> > doesn't find it. Do you have any more suggestions for why this might
> > happen? Can you point me toward the code in iPXE that is supposed to
> > locate the SNP interface and connect to it?

> It's in drivers/net/efi/snponly.c.  From a quick look at the code, it seems as
> though it will only attach to the SNP from which the iPXE binary was loaded
> (i.e. it's the functional equivalent of arch/i386/drivers/net/undionly.c).
>
> It should be possible to create an iPXE EFI driver that will attach to any SNP
> device within the system and call snpnet_probe().  You could model this on the
> code in interface/efi/efi_pci.c, which attaches to any PCI device within the
> system and calls pci_probe().

Thanks! This is what I did. I changed snpbus_probe to call LocateHandle to find a handle that supports SNP and it now connects to my driver.

> > After I got some debugging output enabled, iPXE prints
> >      EFIPCI DRIVER_SUPPORTED 0x3de92f90 (0x0)
> >      EFIPCI device 0x3de92f90 is not a PCI device
> > In fact, 0x3de92f90 isn't even a valid handle; as far as I know, EFI
> > handles are small integers, not memory addresses.

> UefiBaseType.h:  typedef VOID * EFI_HANDLE;
>
> (Type checking?  Who needs type checking?  Let's make one of the most
> frequently used EFI data types transparently cast to or from any pointer
> type!)

I'm with you there. (Though with the frequency of casts in the EDK code, it hardly matters.)

I still don't understand why the 'dh' command only lists handles with small integer values. But it doesn't matter to me now--that code isn't part of snponly.

I appreciate the assistance.

Philip