Re: [Qemu-devel] [Qemu-ppc] [PATCH 28/58] device tree: give dt more size

[Alexander Graf]

On 15.09.2011, at 05:19, David Gibson wrote:

> On Wed, Sep 14, 2011 at 10:42:52AM +0200, Alexander Graf wrote:
>> We currently load a device tree blob and then just take its size x2 to
>> account for modifications we do inside. While this is nice and great,
>> it fails when we have a small device tree as blob and lots of nodes added
>> in machine init code.
>> 
>> So for now, just make it 20k bigger than it was before. We maybe want to
>> be more clever about this later.
> 
> In fact, one of the few things I can think of that might justify
> qemu's "abstraction" of the libfdt interface, is that the wrappers
> could be modified to detect -FDT_ERR_NOSPACE and realloc()
> appropriately.

Oh, yeah, that sounds like a very good idea!

> Otherwise the wrappers, which are limited and not notably simpler to
> use than the raw libfdt functions seem pretty pointless to me.
> 
> Not that I'm biased as the author of libfdt or anything :).

I agree that the wrappers are not all that overly useful atm. I was actually 
very close to just ripping them out completely instead of extending them for 
new functionality. I did have the feeling that wrapping libfdt would give us a 
few benefits, maybe even the chance of getting rid of #ifdefs in target code.

Could you please put this on your todo list? We should probably force every 
target code in QEMU to only use the wrappers and dynamically realloc() in them.


Alex