Hi Leif, I agree the behaviour is not immediately obvious when looking only at the PR. I was initially confused as well when first reviewing the issue.
The DynamicTablesManagerDxe installs an event notification for when both gEfiAcpiTableProtocolGuid and gEfiSmbiosProtocolGuid become available, see https://github.com/tianocore/edk2/blob/master/DynamicTablesPkg/Drivers/DynamicTableManagerDxe/DynamicTableManagerDxe.c#L61-L90 The EfiCreateProtocolNotifyEvent() invokes the event notification handler function in the following situations 1. if the protocol instance already exists 2. Whenever the protocol is installed/reinstalled 3. At least once even if the protocol is not installed. The documentation extract for the last case is as below > If there are no instances of ProtocolGuid in the handle database at the time this function is invoked, > then the notification function is still executed one time Please see https://github.com/tianocore/edk2/blob/master/MdePkg/Library/UefiLib/UefiLib.c#L106-L108 The check in the PR is handling the case 3 above. The DEPEX was removed as we want to support platforms that generate only ACPI tables without requiring SMBIOS support. The previous DEPEX effectively enforced both protocols as load-order dependencies, which prevented this usage model. The current functionality should allow processing of ACPI tables or SMBIOS tables whenever the protocol becomes available. Hope that clarifies the situation. Regards, Sami Mujawar From: Leif Lindholm <[email protected]> Date: Tuesday, 19 May 2026 at 15:43 To: Sami Mujawar <[email protected]> Cc: Andrew Fish <[email protected]>; Kinney, Michael D <[email protected]>; Ard Biesheuvel <[email protected]>; Michael Kubacki <[email protected]>; edk2-devel-groups-io <[email protected]>; [email protected] <[email protected]>; Pierre Gondois <[email protected]>; [email protected] <[email protected]> Subject: Re: Request to include in edk2-stable202605 - [tianocore/edk2] DynamicTablesPkg: Fix dependency issues with consumed protocols (PR #12562) This PR fails the path of least surprise quite badly. It "fixes" a PR that removed a DEPEX that was maintaining load order, and it does this by making the event handler function called when a protocol is available silently return in case the protocol was not in fact available. This feels like a design issue that needs fixing, not a symptom that needs to be hidden a few days before a stable tag after being in the tree since September. Best Regards, Leif On Tue, 19 May 2026 at 14:16, Sami Mujawar <[email protected]<mailto:[email protected]>> wrote: Dear Tianocore Stewards, The PR https://github.com/tianocore/edk2/pull/12562 is an essential bug fix and has been reviewed. I do not have access to set the milestone to edk2-stable202605. Is it possible to set the milestone and include this fix in the stable tag edk2-stable202605, please? Warm regards, Sami Mujawar From: Oleksandr Tymoshenko <[email protected]<mailto:[email protected]>> Date: Tuesday, 19 May 2026 at 00:05 To: tianocore/edk2 <[email protected]<mailto:[email protected]>> Cc: Sami Mujawar <[email protected]<mailto:[email protected]>>; Review requested <[email protected]<mailto:[email protected]>> Subject: Re: [tianocore/edk2] DynamicTablesPkg: Fix dependency issues with consumed protocols (PR #12562) [X]gonzoua left a comment (tianocore/edk2#12562)<https://github.com/tianocore/edk2/pull/12562?email_source=notifications&email_token=ACY3LHYWGCYAX4CSVHVY3YD43OJJ5A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINBYGMYDANBUGU3KM4TFMFZW63VQOJSXM2LFO5PXEZLROVSXG5DFMSSWK5TFNZ2LK4DSL5RW63LNMVXHIX3POBSW4X3DNRUWG2Y#issuecomment-4483004456> Gentle reminder: I think this is a regression and should be fixed in stable tag. — Reply to this email directly, view it on GitHub<https://github.com/tianocore/edk2/pull/12562?email_source=notifications&email_token=ACY3LHYWGCYAX4CSVHVY3YD43OJJ5A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINBYGMYDANBUGU3KM4TFMFZW63VQOJSXM2LFO5PXEZLROVSXG5DFMSSWK5TFNZ2LK4DSL5RW63LNMVXHIX3POBSW4X3DNRUWG2Y#issuecomment-4483004456>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ACY3LH6W56RYFM42C7QFEUD43OJJ5AVCNFSM6AAAAACYWUAVL6VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DIOBTGAYDINBVGY>. 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