Re: [PATCH v4 00/18] hw/avr: Introduce few Arduino boards

[Richard Henderson]

On 1/21/20 11:23 AM, Philippe Mathieu-Daudé wrote:
>> 4. There is difference between -bios and -kernel (arduino boars crash when 
>> -bios is used, but this seems because I run avr6 on avr5 CPU). I would be 
>> happy if you explained what is the difference between these two arguments.
> 
> qemu man page is not very helpful...
> 
>        -bios file
>            Set the filename for the BIOS.
> 
>        -kernel bzImage
>            Use bzImage as kernel image. The kernel can be either a
> Linux kernel or in multiboot format.
> 
> Paolo, Peter, do you have a simple explanation?

It depends on your target board.  They *can* do very different things.

E.g. for "pc" (x86) machine, -bios sets the seabios image to use, and -kernel
loads a kernel image that seabios will invoke.

E.g. for "dp264" (alpha) machine, -bios sets the palcode image to use and
-kernel loads a kernel image.  Note that in this case, the alpha kernel relies
on palcode services, so both must be present for the system to work.

E.g. for "virt" (arm) machine, -bios loads a raw image at which the reset
vector will be pointed, whereas -kernel loads a linux kernel image and follows
the arm-linux kernel boot protocol.  In other words the images are treated very
differently.

I don't know what, if anything, an avr kernel would require from boot services.
 I suspect the two options *could* be treated identically.


r~