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Secure Boot support was originally addded to OvmfPkg on 2012-Mar-09, in SVN r13093 (git 8cee3de7e9f4), titled OvmfPkg: Enable secure-boot support when SECURE_BOOT_ENABLE==TRUE At that time the image verification policies in SecurityPkg/SecurityPkg.dec were: - option ROM image: 0x00 (ALWAYS_EXECUTE) - removable media image: 0x05 (QUERY_USER_ON_SECURITY_VIOLATION) - fixed media image: 0x05 (QUERY_USER_ON_SECURITY_VIOLATION) The author of SVN r13093 apparently didn't want to depend on the SecurityPkg defaults for the latter two image origins, plus the ALWAYS_EXECUTE policy for option ROM images must have been deemed too lax. For this reason SVN r13093 immediately spelled out 0x05 (QUERY_USER_ON_SECURITY_VIOLATION) within OvmfPkg for all three image origins. Fast forward to 2013-Aug-28: policy 0x05 (QUERY_USER_ON_SECURITY_VIOLATION) had been forbidden in the UEFI spec, and SVN r14607 (git db44ea6c4e09) reflected this in the source code: - The policies for the latter two image origins were switched from 0x05 to 0x04 (DENY_EXECUTE_ON_SECURITY_VIOLATION) in SecurityPkg, - the patch changed the default policy for option ROM images too, from 0x00 (ALWAYS_EXECUTE) to 0x04 (DENY_EXECUTE_ON_SECURITY_VIOLATION), - any other client DSC files, including OvmfPkg's, underwent a whole-sale 0x05 (QUERY_USER_ON_SECURITY_VIOLATION) -> 0x04 (DENY_EXECUTE_ON_SECURITY_VIOLATION) replacement too. The practical result of that patch for OvmfPkg was that the explicit 0x04 settings would equal the strict SecurityPkg defaults exactly. And that's what we have today: the "override the default values from SecurityPkg" comments in OvmfPkg's DSC files are stale, in practice. It is extremely unlikely that SecurityPkg would change the defaults from 0x04 (DENY_EXECUTE_ON_SECURITY_VIOLATION) any time in the future, so let's just inherit those in OvmfPkg. Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Fu Siyuan <siyuan.fu@intel.com> Cc: Chao Zhang <chao.b.zhang@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Fu Siyuan <siyuan.fu@intel.com> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> Reviewed-by: Chao Zhang <chao.b.zhang@intel.com> git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19613 6f19259b-4bc3-4df7-8a09-765794883524