[ipxe-devel] Cannot boot to iPXE server with RealTek UEFI PXE boot after enabled the DMAr (IOMMU)

[Angus.Ho at Dell.com]

Hi iPXE developer,

This is Angus from Dell Desktop BIOS team.

Our Dell factory met one issue that the system cannot boot to iPXE server with UEFI PXE boot on Dell NPI platform (Intel CometLake-S) after BIOS enabled DMAr (IOMMU).

After AMI and ODM investigation:


  1.  This issue only occurred on the platform which is used Realtek Lan chip, RTL8111HS.
  2.  This issue cannot be duplicated with Intel Lan (Intel 219-V or i219-LM).
  3.  System can boot to WDS server or Rambo server successfully even the Lan chip is the Realtek.
  4.  If we disable VT-d in BIOS SETUP (disable VT-d means the DMAr/IOMMU feature will be disabled), this issue is gone.

The follows is the RealTek investigation result, have you met this issue before? Or do you have any suggestion for this issue? Is it possible that current iPXE server only support Intel Lan chip after BIOS enabled DMAr (IOMMU)?

===============================

The RealTek investigation result:

For the 3.1 S/W UNDI Start command, the CPB structure shown below must be filled in, but we found below function is NULL.

CpbPtr_31->Map_Mem
UINT64  Map_Mem;
 //
 // Map virtual memory address for DMA.
 // This field can be set to zero if there is no mapping
 // service.
 //
 // VOID
 // Map_Mem(
 //  IN UINT64  UniqueId,
 //  IN UINT64  Virtual,
 //  IN UINT32  Size,
 //  IN UINT32  Direction,
 //  OUT UINT64  PhysicalPtr);


Refer to below picture.

?   Green block is the process while bios loading lan uefi driver.There is return value for Map_Mem function.

?   Red block is iPXE procedure, function "CpbPtr_31->Map_Mem" is NULL.
[cid:image015.png at 01D5BC42.2A279C00]


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