[coreboot] 3 questions about coreboot

[ali hagigat]

Stefan,

BIOS chip is not connected to CPU directly after reset!!

It is connected to the south bridge and it is on the PCI bus.

When CPU gets ready  to read from F000:FFF0, this request travels to BIOS
chip.

> I mean the hardware immediately accesses BIOS chip after reset but at
> > some point all memory read/write cycles are claimed by 945 and memory
> > controller?
> > No, that assumption is not true.
>

If not so what happens? CPU does not have address/data buses directly
attached to the BIOS chip.

Thank you to answer the questions.


On Wed, Jul 7, 2010 at 2:16 PM, Stefan Reinauer <
stefan.reinauer at coresystems.de> wrote:

>  On 7/7/10 6:42 AM, ali hagigat wrote:
> > My chipset is Intel Core2Due/945/ICH7.
> >
> > I have 3 questions.
> >
> > First question:
> > I wonder how PCI memory read cycles can read an instruction from
> > F000:FFF0 right after reset which is the first instruction of BIOS.
> x86 CPUs are designed like that. Go read the Intel®64 and IA-32
> Architectures Software Developer's Manuals:
> http://www.intel.com/products/processor/manuals/
>
> > Does Coreboot writes into PCI configuration space of Device 31 of
> > ICH7-south bridge(LPC controller)? before initializing the
> > configuration space of Device 0 of 82945(which is memory controller)?
> What do you mean by "initializing the configuration space of Device 0 of
> 82945" ?
>
> Generally, a lot of work happens before RAM is initialized. Go read the
> source code for further details.
>
> > I mean the hardware immediately accesses BIOS chip after reset but at
> > some point all memory read/write cycles are claimed by 945 and memory
> > controller?
> No, that assumption is not true.
>
> > Second question:
> > What is the code flow of Coreboot? Where does
> > it start? and how it contines?
> It starts with the reset vector, which is in the "bootblock". That
> bootblock loads further modules.
>
>
> > Third question:
> > Inside src/mainboard/kontron/986lcd-
> > m/acpi we have some asl files.
> > What language they have been written in? Like superio.asl
>
> The language is called ACPI Control Message Source Language (short:
> ASL). Go read http://www.acpi.info/DOWNLOADS/ACPIspec40a.pdf and
> http://acpica.org/documentation/
>
>
> Stefan
>
> --
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>
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