Hi, Wang Fei,
   Thanks for responding my post.  I put my own  boot loader in the MBR,  and I’m sure that my code can’t print that meassage. On the other hand, the error happens before seabios load the MBR at 0x7c00.  Thus I think it isn’t possible from MBR. 
Yang Zhang

On Aug 20, 2014, at 6:42 AM, WANG FEI <wangfei.jimei@gmail.com> wrote:

Yang Zhang,

Is it possible the error message from MBR?


On Mon, Aug 18, 2014 at 8:50 PM, Yang Zhang <udapostate@gmail.com> wrote:
 I meet a boot failure when I use seabios to load my own boot loader  on virtual machine.  The error message printed on screen say that ”Error loading from operating system”, which neither comes from seabios or my boot loader(I have read the source code of seabios, but I didn’t find any code can print a such message). Actually I don’t  know where  the error message come from. Therefore I have to trace the execution of seabios and my boot loader. It seems like the error happens before seabios load my boot loader(in the file romlayout.S), but I don’t know the exact position. Can anyone tell me how to print something to screen in the romlayout.S? (I can’t use gdb to debug because the virtual machine is running on our own  OS). Thank you very much.
Yang Zhang

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