Debugging window 10 while boot
 

Hi there :)
I have to debug MBR of win 10 64byte to try to understand an utility who load before Windows.
Sincerelly I even don't know were to start.
I have try many example for debug with Virtualbox, but not for boot process.
May you help me f.e. linking some adeguate tutorials?
I do like x64dbg, so a solution x64dbg+Virtualbox for me may be my dream....
Thanks

Dan

p.s. Mr. Moderator, may I reveal of what prog I am speaking about?

Practically speaking, setting up a BOCHS emulator and using IDA Pro debugger is a pretty good way to go about this. Not sure but likely x64dbg can do this as well. The only way to debug this early in the boot process is with some sort of emulation unless your BIOS had some really special remote debugging features. Though in a VM it would seem possible I've never seen a good way to go about this. Even remote kernel debugging is of course too late for studying the MBR.

https://www.codeproject.com/Articles/36907/How-to-develop-your-own-Boot-Loader#_Toc231383186

https://cyberview.wordpress.com/2010/09/16/debugging-bios-under-vmware-using-idas-gdb-debugger/

These articles should be useful.

Another choice: VisualKernel or VisualGDB with Vmware GDB Stub or QEMU

Many thanks to all for your effort, I have read all, and even other threads, but for me is un "impossible mission" ;-)
As last resource I have also try with "windebug essential"+Virtualbox, but debugging kernel mode is different from debugging from bios-post......

just concentrate on utility