Re: [PATCH] riscv: Generate devicetree only after machine initialization is complete

[Guenter Roeck <linux@roeck-us.net>]

On 7/3/23 00:46, Philippe Mathieu-Daudé wrote:
> On 3/7/23 05:46, Guenter Roeck wrote:
>> If the devicetree is created before machine initialization is complete,
>> it misses dynamic devices. Specifically, the tpm device is not added
>> to the devicetree file and is therefore not instantiated in Linux.
>> Create devicetree in virt_machine_done() to solve the problem.
> 
> This makes sense, but what about the other archs/machines?
> Shouldn't we fix this generically?
> 

I had a brief look into various implementations. To me the code looks
all very machine specific. I don't think it can be solved generically
(if other machines are even affected), but then I am not a qemu expert
and may be wrong.

Guenter

>> Cc: Alistair Francis <alistair23@gmail.com>
>> Fixes: 325b7c4e75 hw/riscv: Enable TPM backends
>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>> ---
>>   hw/riscv/virt.c | 9 ++++++---
>>   1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
>> index ed4c27487e..08876284f5 100644
>> --- a/hw/riscv/virt.c
>> +++ b/hw/riscv/virt.c
>> @@ -1248,6 +1248,11 @@ static void virt_machine_done(Notifier *notifier, void *data)
>>       uint64_t kernel_entry = 0;
>>       BlockBackend *pflash_blk0;
>> +    /* create devicetree if not provided */
>> +    if (!machine->dtb) {
>> +        create_fdt(s, memmap);
>> +    }
>> +
>>       /*
>>        * Only direct boot kernel is currently supported for KVM VM,
>>        * so the "-bios" parameter is not supported when KVM is enabled.
>> @@ -1508,15 +1513,13 @@ static void virt_machine_init(MachineState *machine)
>>       }
>>       virt_flash_map(s, system_memory);
>> -    /* load/create device tree */
>> +    /* load device tree */
>>       if (machine->dtb) {
>>           machine->fdt = load_device_tree(machine->dtb, &s->fdt_size);
>>           if (!machine->fdt) {
>>               error_report("load_device_tree() failed");
>>               exit(1);
>>           }
>> -    } else {
>> -        create_fdt(s, memmap);
>>       }
>>       s->machine_done.notify = virt_machine_done;
>