ArmVirtPkg: Resolve RngLib via RngDxe for TRNG support

Gerd reports that ArmVirtQemu running under KVM lost network boot support on systems that do not implement the RNDR/RNDRRS system registers, which provide an architectural, CPU-based source of random numbers. Under KVM, the TRNG SMCCC is available as a fallback, which is exposed via RngDxe but not via the base RngLib library. This means that direct users of RngLib, such as OpensslLib, have no access to the TRNG based entropy source. Let's fix this by resolving RngLib dependencies for UEFI_DRIVER type drivers via DxeRngLib, which uses the protocol exposed by RngDxe internally. Signed-off-by: Ard Biesheuvel <[email protected]>
coreboot · Sep 3, 2024 · afba535 · afba535
1 parent 8504d2b
commit afba535
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/ArmVirtPkg/ArmVirt.dsc.inc b/ArmVirtPkg/ArmVirt.dsc.inc
@@ -232,6 +232,10 @@
   DebugLib|ArmVirtPkg/Library/DebugLibFdtPL011Uart/DebugLibFdtPL011UartFlash.inf
 !endif
 
+[LibraryClasses.common.UEFI_DRIVER]
+  # resolve RngLib via RngDxe's EFI_RNG_PROTOCOL for UEFI_DRIVER type drivers such as TlsDxe
+  RngLib|MdePkg/Library/DxeRngLib/DxeRngLib.inf
+
 [LibraryClasses.common.DXE_CORE]
   HobLib|MdePkg/Library/DxeCoreHobLib/DxeCoreHobLib.inf
   MemoryAllocationLib|MdeModulePkg/Library/DxeCoreMemoryAllocationLib/DxeCoreMemoryAllocationLib.inf