How to display something on the screen while the kernel starting up?

My platform is:
A CEPC-based x86 machine
A CF card to store NK and HIVE registry
Using the x86 biosloader as our boot loader

Now I can display a progress bar by biosloader to indicate the loading
status of NK.bin.
But after that, the kernel takes a long time (about 20s) to startup,
and the screen is totally black in this time, until the desktop shows
up.

So I want to display something on the screen to indicate the kernel
startup status, but how to implement this? and from which step of the
NK loading process?
I think that it maybe the HIVE loading process which takes a long
time, Is there a chance to operate the screen before that?

I cannot change the display driver because there is no source code in
the BSP.

Any suggestions? Help please!

Best regards
Atsing

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