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This will have Invalid PE header magic issue if use the default sbsign in ubuntu 2220.04, need rebuild the sbsigntools, refer the Step 3 to solve this issue ! If no Invalid PE header magic issue then just skip Step 3.
Step 3 (Optional): Download and rebuild the latest sbsigntools
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$ ./sbsigntools/src/sbsign --key DB.key --cert DB.crt --output EmptyApplication-Riscv.efi.signed EmptyApplication-Riscv.efi
Step 4: Sign the EFI applicaiton by using private key, and copy Copy the public key to the fat disk
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