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

[Alexander Graf]

On 19.06.2012, at 20:39, Blue Swirl wrote:

> On Tue, Jun 19, 2012 at 12:54 PM, Alexander Graf <address@hidden> wrote:
>> 
>> 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 :).
> 
> There's g_vasprintf(), which could be used to implement qemu_asprintf().

Oh? Certainly something to look at. Having all those statically sized arrays on 
the stack makes me nervous.

> By the way, what is your plan about PPC patch queue, for example AREG0
> patches? There may be some need for rebasing already.

I already did rebase them, no worries :). I'll send out a PULL request soon.


Alex