OSDev.org

Hi,
I've added Multiprocessor support on my own os.

APs trampoline code successfully starts, but I've a problem with BIOS int 10h calling for Video Output. Simply nothing is visualized.

Is it possible to use the BIOS interrupt services from APs boot code (still real mode)?

Thanks!

Yes, technically it should be possible, but trust me, you don't want to use it for any reason whatsoever. Printing using int 0x10 would interfere with your ordinary printing routines, and using any other interrupt would be silly (getting info? loading data? both already done on the BP).

If you really want to print from realmode, why not copy the message into a buffer that is than printed by the BP?

You are right, I've noticed some interferences... finally it's worked but the string "Hello World" was printed like "Hlo orld" or similar (it changed at every boot).
However I used 0x10 int only for debug purpose. When I realized that the AP was booted I've removed the print in real mode.