[coreboot] kernel payload

[Duncan Guthrie]

Hi there,

I'm a little confused by some of this email - at the start you seem to 
be asking about your "distribution" - I assume this is your operating 
system, and as a result I will answer that first part as far as I 
understand the question.

I think you are confusing a Linux payload loaded by Coreboot, and the 
kernel that your operating system uses.
Coreboot has the ability to load various payloads, including SeaBIOS, 
GNU Grub2, Filo, and Linux (this is a non-exhaustive list, one should 
note).
These are almost always loaded from the flash chip directly. See the 
following page for more information: https://www.coreboot.org/Payloads.
What you will likely want is to load SeaBIOS, which can then load your 
operating system as usual.

As for creating a Linux payload, if you look in menuconfig, and select a 
Linux payload. You will see that you can specify a kernel binary, and an 
initrd optionally. The basic requirement is a valid bzImage. Optionally 
specifying an initrd environment allows us to boot this directly, which 
is very useful as a recovery environment.

Perhaps some others can answer your question about the last part. I wish 
you good luck.

-Duncan

On 05.05.2017 19:11, Healer64 via coreboot wrote:
> I've looked through all the docs I can find on this, but there doesn't
> seem to be much available. Hopefully some of you can help answer my
> questions. My distribution includes a vmlinuz kernel. Do I need to
> compile a custom bzimage kernel or will the stock kernel suffice?
> 
> I am using lvm on a dmcrypted disk for the root filesystem. Presumably
> these binaries and helper scripts will be needed in the initrd. So far
> the only help I've seen on creating the initrd for the payload is
> Ron's email to this list where he says
> 
> "Your best bet is to do the standard trivial initramfs with a simple
> program: main(){printf("hin"); while (1);} Let's pretend it's called
> mymain.c cc -o mymain -static mymain.c put that in your prototype root
> file system with the name init. make sure you create /dev/console.
> Then bundle it all up with cpio and you've got an initramfs"
> 
> That seems to describe more of a shim than a true initrd. Also he
> mentions initramfs whereas menuconfig asks for initrd. Which is
> correct? I don't see any reference to filesystem drivers in Ron's
> email, but surely they are required to mount the root. I'm guessing
> this is a test example that is not intended to boot.
> 
> Can anyone provide help or instructions on an actual bootable
> initrd/initramfs? Can a pointer to the initramfs in /boot be used?
> What kind of size will it be? My rom is limited to 8Mb and the kernel
> is over 5Mb.
> 
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