[coreboot] coreboot debugging with qemu-x86

[Gerd Hoffmann]

On Sa, 2015-05-09 at 16:28 +0530, Saket Sinha wrote:
> HI Ajay,
> 
> > Try giving
> > -m 1g
> >
> 
> 
> Doesn't help. Same output.
> 
> 
> saket at saket-Notebook-PC:~/coreboot$ qemu-system-x86_64 -L . -bios
> build/coreboot.rom -nographic
> qemu: fatal: Trying to execute code outside RAM or ROM at 0x00000000000a0000
> 
> EAX=00000001 EBX=00000000 ECX=00000000 EDX=00000663
> ESI=00000000 EDI=00000000 EBP=00000000 ESP=0000fffa
> EIP=0009ffd6 EFL=00000082 [--S----] CPL=0 II=0 A20=1 SMM=0 HLT=0
> ES =0000 00000000 0000ffff 00009300
> CS =0000 00000000 0000ffff 00009b00

No, its not the same output.  Quoting original post:

EIP=0000fff0 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
    ^^^^^^^^
ES =0000 00000000 0000ffff 00009300
CS =f000 ffff0000 0000ffff 00009b00
    ^^^^

That is the reset vector, i.e. something going seriously wrong on the
very first instruction executed.  rom image being garbage or something
like that.  Check your build environment.  Broken toolchain?  Disk full?

The new crash is at some completely different place, so coreboot at
least starts executing.

Try this ...

  qemu -bios coreboot.rom \
    -chardev stdio,id=log \
    -device isa-debugcon,iobase=0x402,chardev=log

... to see the coreboot log (assuming coreboot comes far enough to
actually produce log output).

cheers,
  Gerd