[SeaBIOS] IDT issue

Kevin O'Connor kevin at koconnor.net
Wed Mar 18 15:43:44 CET 2015


On Tue, Mar 17, 2015 at 06:42:06PM +0530, Naresh G. Solanki wrote:
> Dear All,
> 
> I'm trying to port coreboot with seabios payload on Intel Atom E6xx based
> board,
> 
> The problem I'm facing is during malloc init, the board reboot & keeps on
> rebooting after displaying malloc init debug message.
> 
> I tried to track it & found that it might probably be due to dummy IDT
> loaded  @seabios entry point (entry_elf)
> 
> Once it reboot I'm finding that breakpoints set are not working.
> Breakpoints are set through JTAG-XDP.
> 
> Can anyone give an idea to how to go about this issue.

SeaBIOS loads a dummy IDT when in 32bit mode, because the code is
never supposed to raise an interrupt (interrupts and NMIs are always
disabled when in 32bit mode).  So, if you're seeing a fault with the
IDT, it likely indicates something is causing a software fault.

If a fault is ocurring in malloc_init(), then I'd check that the
memory between 0xc0000-0x100000 is fully read/writable.  You could
also try disabling CONFIG_MALLOC_UPPERMEMORY to see if that changes
behavior.  malloc_init() is also called right after self-relocation,
so check that the memory map that coreboot provides is accurate.  You
could also try disabling CONFIG_RELOCATE_INIT to see if that changes
the fault.

-Kevin



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