coreboot and seabios

[rene de zwart]

I have been trying to make a coreboot rom and have a few questions c.q.
confirmations.

As far as I understand the process

. Coreboot has to initialize the memory to 32bit flatmode and call in
layout.S:entry_elf(). see https://www.seabios.org/Execution_and_code_flow
 . seabios starts and does it's magic
 . seabios starts the linux kernel According to the linux bootprotocol
(Documentation/x86/boot.rst)

The linux kernel runs my computer perfect so many answers could be answered
by the kernel source.
as the same held for seabios and intel documentation

. Linux drivers/i2c/busses:
 .. i2c-i801.c
 .. i2c-smbus.c
 . Linux arch/x86/boot:
 .. main.c
 .. pm.c
 . Seabios
 .. docs/memory_model.md
 . Intel® 965 Express Chipset Family
 .. 82p965.pdf Is this the correct file?

questions

[rene de zwart]

sorry I'm typing on a laptop and my thick vingers hit something and  off,
the email,  went.
. It seems almost to simple to be true?
. Looking thru corebootsrc/mainboard I see so many files per mainboard
that I'm (even more) confused There has been a lot of work to produce those
files

.  what I have not found yet is where are the ( ??DT) acpi tables in
seabios? do  i need to extract those en use the cbfstool to put them in the
rom?
. I'm trying to get my machine working with a free open source bios I'm not
looking into bug fixing (yet)

Thanks Rene

On Sun, Jan 9, 2022 at 10:50 AM rene de zwart  wrote:
> I have been trying to make a coreboot rom and have a few questions c.q.
> confirmations.
>
> As far as I understand the process
>
> . Coreboot has to initialize the memory to 32bit flatmode and call in
> layout.S:entry_elf(). see https://www.seabios.org/Execution_and_code_flow
>  . seabios starts and does it's magic
>  . seabios starts the linux kernel According to the linux bootprotocol
> (Documentation/x86/boot.rst)
>
> The linux kernel runs my computer perfect so many answers could be
> answered by the kernel source.
> as the same held for seabios and intel documentation
>
> . Linux drivers/i2c/busses:
>  .. i2c-i801.c
>  .. i2c-smbus.c
>  . Linux arch/x86/boot:
>  .. main.c
>  .. pm.c
>  . Seabios
>  .. docs/memory_model.md
>  . Intel® 965 Express Chipset Family
>  .. 82p965.pdf Is this the correct file?
>
> questions

[Michał Żygowski]

Hi Rene,

On 09.01.2022 11:27, rene de zwart wrote:
> sorry I'm typing on a laptop and my thick vingers hit something and  
> off, the email,  went.
> . It seems almost to simple to be true?
> . Looking thru corebootsrc/mainboard I see so many files per mainboard  
> that I'm (even more) confused There has been a lot of work to produce 
> those files

the number of files and lines of code per mainboard is really kept to 
minimum, containing only the exact board specific configuration. When 
compared to the common code leveraged across multiple platforms, 
mainboard code is very small.
> .  what I have not found yet is where are the ( ??DT) acpi tables in 
> seabios? do  i need to extract those en use the cbfstool to put them in 
> the rom?
> . I'm trying to get my machine working with a free open source bios I'm 
> not looking into bug fixing (yet)

SeaBIOS detects the ACPI tables that are produced by coreboot and parses 
them for its own needs (e.g. APM). For x86 you don't have a device tree 
like for ARM. Typically SeaBIOS is used as a coreboot's payload. 
coreboot loads SeaBIOS as an ELF file and handles any needed relocations 
and calls the entry point, so you don't have to worry about anything 
like that.

If you are looking for open source firmware/BIOS support I advise to 
drop a mail to [e-mail] instead where community might help 
you get your machine working with coreboot. You would have to provide 
some basic information about your board:

- workstation/laptop/singe board computer
- architecture (x86, ARM, etc.)
- processor, chipset model
- any additional components like Super I/Os (for serial ports, PS/2 and 
fan control on workstations) or Embedded Controllers (for laptop 
keyboards, battery charging and fan control)
> Thanks Rene

Best regards,