Re: raspi3b - dumpdtb

Re: raspi3b - dumpdtb

[Philippe Mathieu-Daudé]

Hi Little,

On 15/3/23 13:43, Little Tree wrote:
> I am using QEMU 6.2.0 to emulate raspi3b (Raspberry Pi 3b). I have used 
> the following command to dump the DTB. It is neither terminating nor 
> dumping the DTB.
> 
> $ qemu-system-aarch64 -machine raspi3b,dumpdtb=test.dtb
> VNC server running on 127.0.0.1:5900 <http://127.0.0.1:5900>
> 
> If I change the machine to 'virt' as shown below, it dumps the DTB and 
> exits. May I know the reason for this? How can I dump the DTB of the 
> raspi3b machine?

While the 'virt' machine _constructs_ a machine adapted to the command
line options, it *produces* the equivalent DTB.

The raspi machines in contrast are not virtual machines, they respect
the physical hardware. Therefore they *consume* already existing dtb
blobs (with the -dtb command line argument).

See for example the test_arm_raspi2_initrd() test in
tests/avocado/boot_linux_console.py which uses the bcm2709-rpi-2-b.dtb
blob file.

> $qemu-system-aarch64 -machine virt,dumpdtb=test.dtb
> qemu-system-aarch64: info: dtb dumped to test.dtb. Exiting.
> 
> Thanks a lot,
>    Little

Regards,

Phil.