Design Project Specifications

Specifications for the protected mode bootable debugger

• It should be able to boot into protected mode from a floppy
• It should support single stepping through the user plugged in code
• The user should be able to plug in some machine code at a specified memory location from a floppy by specifying , sector and track.
• However the machine code given by the user to be debugged should be a protected mode ring 3 32 bit code.
• The debugger should be capable of dumping the contents of registers
• The debugger should also be able to dump the specified no. of bytes from a given segment:offset onto the screen
• The debugger should be able to print contents of the 386 tables like IDT,GDT,LDT,TSS.
• The user should be able to change its register contents.
• As the debugger is running in protected mode the BIOS routines for I/O cannot be used.
• The debugging will be done with the support of the debug registers ,software breakpoints and the tracing capabilities provided by 386.

Caveat

• No support for paging will be there .
• There will be no filesystem support for the floppy ie the user will have to specify the size and location of the code in terms of sector and track no.
• This debugger can only be used to debug protected mode code , hence we can't debug the bootup sequence as it works in real mode.