See the following post
By default, bios access level is assigned as either User or Admin. Setting control access flags in setup data changes the level required to see the corresponding option.
Control Access Definitions
CONTROL_ACCESS_DEFAULT 0 //Do not override VFR
CONTROL_ACCESS_EXT_USER 1 //Admin - Editable; User - Editable;
CONTROL_ACCESS_USER 2 //Admin - Editable; User - Visible but not editable;
CONTROL_ACCESS_ADMIN 3 //Admin - Editable; User - Invisible;
Flags definition, values on the right are amounts of bits
struct _CONTROL_FLAGS //32 bit structure containing the attributes for a specific control
{
UINT32 ControlVisible : 1;//Whether or not a control is shown
UINT32 ControlAccess : 2;//Access to control
UINT32 ControlReset : 1;//Whether or not changing a value requires a system reset
UINT32 ControlReadOnly : 1;//Whether or not the control is read only
UINT32 ControlInteractive : 1;//Whether the Control is interactive or not
UINT32 ControlEvaluateDefault : 1;//If set Default is obtained by expression evaluation
UINT32 Reserved1 : 1;
UINT32 ControlRefresh : 8;//Refresh timer (in 0.1s intervals)
UINT32 RefreshID : 1;
UINT32 ControlRWEvaluate : 1;//set 0 if read/write expression is not found otherwise set
UINT32 ControlReconnect : 1;//Whether or not changing a value requires a system reconnect
UINT32 BitFieldVarstore : 1;
UINT32 Reserved2 : 12;
};
So 0x29 (0010_1001) means ControlVisible = TRUE, ControlAccess=DEFAULT, ControlReset=TRUE, ControlInteractive=TRUE.
0x9 is the same, but ControlInteractive=FALSE.
0x5 means ControlVisible = TRUE, ControlAccess=ACCESS_USER.
It required patching PEFirmwareUpdateDxe RAM ImageHandle in multiple places. And it’s not as simple to share the method as you might think, because patterns are different for your board.
After all, it’s not confirmed whether the checksum bypass works. Would you really like to test it?
You right, if you get the ch314a it wouldn’t require any more software fiddling to flashe the chip.