> On 9 Oct 2025, at 16:29, Peter Maydell <[email protected]> wrote:
>
> On Thu, 9 Oct 2025 at 14:26, Alexander Gryanko <[email protected]
> <mailto:[email protected]>> wrote:
>>
>>
>>
>>> On 7 Oct 2025, at 16:11, Igor Mammedov <[email protected]> wrote:
>>>
>>> On Sat, 4 Oct 2025 23:19:09 +0300
>>> Alexander Gryanko <[email protected]> wrote:
>>>
>>>> Currently, pvpanic is available in three device types: ISA,
>>>> MMIO, and PCI. For early stages of system initialisation
>>>> before PCI enumeration, only ISA and MMIO are suitable.
>>>> ISA is specific to the x86 platform; only MMIO devices
>>>> can be used for ARM. It is not possible to specify a
>>>> device as on the x86 platform (-device pvpanic); the
>>>
>>> perhaps ARM folsk know better, don't we have some
>>> user create-able sysbus devices? Can it be implemented
>>> as such, so we would avoid creating built-in device?
>>
>> As a QEMU user, I expected there to be a way to specify a dtb from a file
>> that could be used as the actual device tree inside the virtual machine.
>> Perhaps there is a way to do this, but I am not very familiar with the QEMU
>> code and do not know how it should work.
>
> You can generally use '-machine dtb=file.dtb'. But note that
> this entirely overrides any internally generated dtb file
> for machines that do that, so for those machine types it's
> mostly a helpful debugging tool.
I added '-machine dumpdtb=qemu.dtb', then converted dtb to dts 'dtc -I dtb -O
dts -o qemu.dts qemu.dtb', added
pvpanic@9060000 {
reg = <0x0 0x09060000 0x0 0x2>;
compatible = "qemu,pvpanic-mmio";
};
Then I compiled qemu without optimisation and set a breakpoint in
‘pvpanic_mmio_initfn'. It was never called with '-machine dtb=file.dtb'. 'info
qtree' also does not show the device. Perhaps I have configured something
incorrectly?
/opt/qemu10/bin/qemu-system-aarch64 \
-S -d guest_errors,unimp -trace enable=device_* -D $CWD/qemu.log \
-trace memory_region_ops_write \
-cpu cortex-a72 \
-m 2048 \
-bios $CWD/QEMU_EFI.fd \
-nographic \
-qmp unix:$CWD/qmp.sock,server,nowait \
-drive if=virtio,format=raw,file=$CWD/market.img \
-chardev
socket,id=ch0,path=$CWD/serial0.sock,reconnect=1,logfile=$CWD/serial0.log \
-serial chardev:ch0 \
-blockdev
driver=file,filename="$CWD/OVMF_VARS.fd",node-name=uefi-vars,read-only=on \
-vnc :0 \
-display none \
-audiodev none,id=none \
-machine virt,dtb=uefi.dtb \
-monitor stdio \
>
> -- PMM
