Catalina 10.15.4: CMOS reset

[Hervé]

A few of us with old C2D/C2Q platforms (mostly desktop) experienced CMOS reset since updating to 10.15.4.

 

During troubleshooting, the issue was pinpointed to 10.15.4's new boot.efi file (located in /S/L/CoreServices) which, as many of us noticed, was displaying some new info when booting in verbose mode.

 

Initially, replacing 10.15.4's boot.efi file with that of an earlier Catalina release or even an earlier macOS version was found to get rid of the problem without adverse affect on booting Catalina 10.15.4. However, this only worked for Hackintosh systems running Clover, not for systems running OpenCore.

10.15.3_boot.efi.zip

File ownership needs to be re-adjusted to root:wheel upon replacement:

sudo chown 0:0 /S*/L*/CoreServices/boot.efi

 

Update: 15 April 2020

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Following further troubleshooting with vit9696, telepati and a few others, vit9696 worked out a temporary workaround for OpenCore in the form of a 5-bytes NVRAM variable wake-failure set to 00 00 00 00 00. All details and explanations are available here.

 

For Clover users, this workaround alternative to replacing boot.efi can implemented as follows in Terminal:

sudo nvram wake-failure=%00%00%00%00%00

Of course, this needs NVRAM to be working properly on the target Hack. For Hacks with no natively-supported NVRAM, it is required to install EMUVariableUEFI.efi Clover module + RC scripts on the Catalina boot volume. Once the variable is set and the system rebooted to take it into account, no more CMOS reset on rebooting from 10.15.4.