[coreboot] a question about coreboot and Bochs emulator

Scott Duplichan scott at notabs.org
Fri Jan 10 04:39:14 CET 2014

ron minnich [mailto:rminnich at gmail.com] wrote:

]A number of us used bochs years ago for coreboot debugging. IIRC it
]"just worked" when we tried it.

I remember in 2008 when a guy named Kevin proposed changing the
bochs bios from asm code to C code because the build environment
for the asm version was next to impossible to setup. Others were
skeptical about his proposal to use gcc for 16-bit x86 code
generation, but it worked out OK. Today that C coded BIOS is the
default coreboot payload. Though I have not used bochs for several
years, I bet SeaBIOS would still work without too much trouble.

But coreboot itself is a different story I imagine. Today, the 
DDR3 memory reference code used by AMD contains elaborate 
algorithms for receiver enable training, DQS read and write
position training, etc. I think it takes a significant amount
of memory controller emulation code to make the AMD DDR3
initialization pass. I imagine the situation is similar for
Intel memory reference code. Same for HT and QPI.

In 2004 I modified bochs enough to boot a production HP ProLiant
DL145 BIOS (http://notabs.org/bochs/). That took some work, but
the work mostly involved adding enough Opteron/AMD8111 PCI config
space emulation to make the AMI BIOS happy. Memory initialization
was relatively simple in those days. In 2004, bochs had no PCI
config space emulation at all as far as I remember.

AMD simnow has enough chipset and memory controller to boot an
unmodified coreboot. The biggest limitation of AMD simnow is
the public version doesn't support fusion and more recent 

Intel can boot unmodified images using Simics, according to
something I read a while back. But I don't think Intel has
a public version of Simics.


]On Thu, Jan 9, 2014 at 5:22 PM, behrouz khosravi <bz.khosravi at gmail.com> wrote:
]> Hello every one. I have searched a lot on the Net to find my answer but
]> I didn't got any helpful results so I decided to use the mailing list. my
]> question is that has any body ported coreboot to Bochs emulator
]> successfully.
]> I know that Qemu or Simnow are available for emulating a platform but I like
]> to test it Bochs.
]> thanks

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