robin.thoni/ipxe - git rthoni.com

Michael Brown 5238c85b62 [efi] Work around broken EFI HII specification The EFI_HII_CONFIG_ACCESS_PROTOCOL's ExtractConfig() method is passed a request string which includes the parameters being queried plus an apparently meaningless blob of information (the ConfigHdr), and is expected to include this same meaningless blob of information in the results string. Neither the specification nor the existing EDK2 code (including the nominal reference implementation in the DriverSampleDxe driver) provide any reason for the existence of this meaningless blob of information. It appears to be consumed in its entirety by the EFI_HII_CONFIG_ROUTING_PROTOCOL, and to contain zero bits of information by the time it reaches an EFI_HII_CONFIG_ACCESS_PROTOCOL instance. It would potentially allow for multiple configuration data sets to be handled by a single EFI_HII_CONFIG_ACCESS_PROTOCOL instance, in a style alien to the rest of the UEFI specification (which implicitly assumes that the instance pointer is always sufficient to uniquely identify the instance). iPXE currently handles this by simply copying the ConfigHdr from the request string to the results string, and otherwise ignoring it. This approach is also used by some code in EDK2, such as OVMF's PlatformDxe driver. As of EDK2 commit 8a45f80 ("MdeModulePkg: Make HII configuration settings available to OS runtime"), this causes an assertion failure inside EDK2. The failure arises when iPXE is handled a NULL request string, and responds (as per the specification) with a results string including all settings. Since there is no meaningless blob to copy from the request string, there is no corresponding meaningless blob in the results string. This now causes an assertion failure in HiiDatabaseDxe's HiiConfigRoutingExportConfig(). The same failure does not affect the OVMF PlatformDxe driver, which simply passes the request string to the HII BlockToConfig() utility function. The BlockToConfig() function returns EFI_INVALID_PARAMETER when passed a null request string, and PlatformDxe propagates this error directly to the caller. Fix by matching the behaviour of OVMF's PlatformDxe driver: explicitly return EFI_INVALID_PARAMETER if the request string is NULL or empty. This violates the specification (insofar as it is feasible to determine what the specification actually requires), but causes correct behaviour with the EDK2 codebase. Signed-off-by: Michael Brown <mcb30@ipxe.org>		9 years ago
contrib	[errdb] Strip platform error code for non-platform-generated errors	12 years ago
src	[efi] Work around broken EFI HII specification	9 years ago
COPYING	[legal] Update GPLv2 licence text	10 years ago
COPYING.GPLv2	[legal] Update GPLv2 licence text	10 years ago
COPYING.UBDL	[legal] Add support for the Unmodified Binary Distribution Licence	10 years ago
README	[doc] Re-add README file	15 years ago

iPXE README File

Quick start guide:

   cd src
   make

For any more detailed instructions, see http://ipxe.org