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.mach...@gmail.com > <mailto:rafaelrodrigues.mach...@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.ma...@assembler.cz > <mailto:r.ma...@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 > > > -- coreboot mailing list: coreboot@coreboot.org http://www.coreboot.org/mailman/listinfo/coreboot
