AdvLoggerPkg: Default PcdAdvancedLoggerHdwPortOsRuntimeDisable to TRUE - #918
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microsoft@1d1b4db changed the behavior of runtime AdvLogger prints to always print to the serial port. This breaks platforms who give up control of the serial port to an OS after ExitBootServices. microsoft@cea5d2a followed on to fix this behavior by introducing PcdAdvancedLoggerHdwPortOsRuntimeDisable to allow returning to the original behavior and disabling the hardware port logging during runtime. However, this commit set the PCD default to FALSE, which left the breaking change behavior in place, which quietly gets picked up by platforms. This commit flips the PCD default to return to the original behavior and not log to the hardware port at runtime by default. Platforms may set this PCD to FALSE if it is safe to do so on their implementation. Signed-off-by: Oliver Smith-Denny <osde@microsoft.com>
apop5
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Jul 13, 2026
makubacki
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Jul 13, 2026
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Description
1d1b4db changed the behavior of runtime AdvLogger prints to always print to the serial port. This breaks platforms who give up control of the serial port to an OS after ExitBootServices.
cea5d2a followed on to fix this behavior by introducing
PcdAdvancedLoggerHdwPortOsRuntimeDisable to allow returning to the original behavior and disabling the hardware port logging during runtime.
However, this commit set the PCD default to FALSE, which left the breaking change behavior in place, which quietly gets picked up by platforms.
This commit flips the PCD default to return to the original behavior and not log to the hardware port at runtime by default. Platforms may set this PCD to FALSE if it is safe to do so on their implementation.
How This Was Tested
Tested on a platform where it is not safe to write to the serial port at runtime. It crashed before this change and boots after it.
Integration Instructions
Platforms will continue to work as they did before 1d1b4db. Platforms who wish to have serial logging at runtime can set
PcdAdvancedLoggerHdwPortOsRuntimeDisable|TRUEin their DSC.