shim is a trivial EFI application that, when run, attempts to open andexecute another application. It will initially attempt to do this via thestandard EFI LoadImage() and StartImage() calls. If these fail (because secureboot is enabled and the binary is not signed with an appropriate key, forinstance) it will then validate the binary against a built-in certificate. Ifthis succeeds and if the binary or signing key are not blacklisted then shimwill relocate and execute the binary.shim will also install a protocol which permits the second-stage bootloaderto perform similar binary validation. This protocol has a GUID as describedin the shim.h header file and provides a single entry point. On 64-bit systemsthis entry point expects to be called with SysV ABI rather than MSABI, so callsto it should not be wrapped.On systems with a TPM chip enabled and supported by the system firmware,shim will extend various PCRs with the digests of the targets it isloading.  A full list is in the file README.tpm .To use shim, simply place a DER-encoded public certificate in a file such aspub.cer and build with "make VENDOR_CERT_FILE=pub.cer".There are a couple of build options, and a couple of ways to customize thebuild, described in BUILDING.