Re: Looking for advise on debugging a non-boot kernel on qemu-system-sh4

[Thomas Huth]

On 21/10/2021 11.49, John Paul Adrian Glaubitz wrote:
> Hello!
>
> I'm regularly building debian-installer packages for Debian's unofficial ports
> which includes sh4 among others. The kernel package and therefore the installer
> package contains a kernel for the SH7751R machine which is emulated by QEMU when
> choosing the "r2d" type.
>
> Unfortunately, I have not yet been able to boot a current kernel on 
> qemu-system-sh4,
> the screen remains blank and there are no error messages. Booting an older 2.6 
> kernel
> works just fine.
>
> I'm using qemu-system-sh4 as follows:
>
> $ qemu-system-sh4 -M r2d -kernel vmlinuz-2.6.32-5-sh7751r -initrd initrd.gz 
> -hda debian.img \
>    -append "root=/dev/sda1 console=tty0 noiotrap"
>
> The old 2.6 kernel from [1] boots fine while the current 5.14.x kernel from [2] 
> does
> not produce any output.
>
> Can anyone enlighten me what I might be missing?

I can't say much about very recent kernels, but FWIW, it was still working 
fine with kernel 4.9 in 2018, see:

 https://www.qemu-advent-calendar.org/2018/#day-9

In case it's just the video driver that is not working anymore, try:

 -append "console=ttySC1" -serial null -serial stdio

... that should hopefully redirect the kernel output to the serial console 
on stdio of the host terminal (at least it does so with the advent calendar 
image that I mentioned above).

 HTH,
  Thomas