10 Jan
2016
10 Jan
'16
9:56 p.m.
On 01/10/2016 10:23 AM, ron minnich wrote:
One thing I think you'd enjoy doing is building the qemu target, setting up qemu with gdb, and just watching what happens, instruction by instruction, as the system boots.
One exercise I liked doing was to rewrite the entire boot flow, from reset vector to protected mode entry. Tested on qemu, put it on hardware, nothing burned.
Alex
ron
On Sun, Jan 10, 2016 at 3:28 AM Rafael Machado <rafaelrodrigues.machado@gmail.com mailto:rafaelrodrigues.machado@gmail.com> wrote:
Hi Peter and Rudolf. Thanks for the answers and tips. They are realy helpfull ! I'll take a look. Rafael R. Machado Em Sáb, 9 de jan de 2016 17:19, Rudolf Marek <r.marek@assembler.cz <mailto:r.marek@assembler.cz>> escreveu: Hi, I guess your question is more general than the coreboot related right? If you have a firmware image dump of the flash (not the file you download from board vendor) then yes, first location to be executed is the instruction located 16 bytes before end of the image. In coreboot see in build/ bootblock_inc.S which also has reset16.inc and entry16.inc which is a real start. Consult the Intel or AMD manual to see the CPU state after reset. The CPU starts in real mode, but CS base is shifted to last 64KB before end of 4GB address space. In general your CPU starts in compatible mode with 8086 manufactured in 1978. Thanks Rudolf -- coreboot mailing list: coreboot@coreboot.org <mailto:coreboot@coreboot.org> http://www.coreboot.org/mailman/listinfo/coreboot