Re: [Qemu-ppc] [Qemu-devel] [PATCH 00/31] PPC: mpc8544ds: Create device tree dynamically

[Alexander Graf]

On 07.06.2012, at 23:09, Blue Swirl wrote:

> On Tue, Jun 5, 2012 at 11:52 PM, Alexander Graf <address@hidden> wrote:
>> Today we have two separate places where we keep information which device
>> is where:
>> 
>>  - hw/ppce500_mpc8544ds.c to instantiate all devices
>>  - pc-bios/mpc8544ds.dtb as device tree to tell the guest about devices
>> 
>> Every time we split crucial information, things can go terribly wrong. If
>> you update one file, but not the other, you can screw things up without
>> realizing it quickly.
>> 
>> The redundancy is also unnecessary, because QEMU already knows all the
>> information at which addresses its devices live. So we can generate the
>> device tree from the same variables - and even have the device tree adjust
>> if something changes in there.
>> 
>> The one functionality we lose with this approach is the ability to manually
>> patch the device tree to contain additional devices. To still be able to do
>> so easily, we introduce a new option -machine dumpdtb=<file> that creates a
>> dtb output file which can be used with -machine dtb=<file> later. In between
>> these 2 executions of QEMU, the dtb can be modified however much you like.
>> 
>> A lot of bits in this patch set are still hardcoded. We also don't accomodate
>> for dynamic creation of device tree nodes when -device is used. This requires
>> a bit more QOM'ification for us to be able to loop through all devices, so we
>> can dynamically create the device tree nodes for them. The basic concept 
>> should
>> still hold as is though.
>> 
>> 
>> Alex
> 
> Please use snprintf() instead of sprintf().

Oh how much I would love to be able to just call asprintf() and call it a day 
:).


Alex