RE: [RFC] fdt:free the fdt reserved memory

[Wang, Yalin]

> -----Original Message-----
> From: Grant Likely [mailto:glikely@xxxxxxxxxxxx] On Behalf Of Grant Likely
> Sent: Thursday, December 04, 2014 6:05 PM
> To: Wang, Yalin; 'robh+dt@xxxxxxxxxx'; 'devicetree@xxxxxxxxxxxxxxx';
> 'pawel.moll@xxxxxxx'; 'mark.rutland@xxxxxxx';
> 'ijc+devicetree@xxxxxxxxxxxxxx'; 'linux-kernel@xxxxxxxxxxxxxxx'
> Subject: RE: [RFC] fdt:free the fdt reserved memory
> 
> On Thu, 4 Dec 2014 14:56:11 +0800
> , "Wang, Yalin" <Yalin.Wang@xxxxxxxxxxxxxx>
>  wrote:
> > > -----Original Message-----
> > > From: Grant Likely [mailto:glikely@xxxxxxxxxxxx] On Behalf Of Grant
> > > Likely
> > > Sent: Wednesday, September 24, 2014 10:45 PM
> > > To: Wang, Yalin; 'robh+dt@xxxxxxxxxx'; 'devicetree@xxxxxxxxxxxxxxx';
> > > 'pawel.moll@xxxxxxx'; 'mark.rutland@xxxxxxx';
> > > 'ijc+devicetree@xxxxxxxxxxxxxx'; 'linux-kernel@xxxxxxxxxxxxxxx'
> > > Subject: Re: [RFC] fdt:free the fdt reserved memory
> > >
> > > On Thu, 18 Sep 2014 17:25:12 +0800, "Wang, Yalin"
> > > <Yalin.Wang@xxxxxxxxxxxxxx> wrote:
> > > > This patch make some change to unflatten_dt_node(), make sure the
> > > > device_node don't reference to fdt raw blob memory, so that we can
> > > > free the raw blob reserved memory after initcalls.
> > > >
> > > > Signed-off-by: Yalin Wang <yalin.wang@xxxxxxxxxxxxxx>
> > >
> > > Do you have any measurements showing a change in available memory
> > > before and after the patch?
> > >
> > Does anyone have a look at this patch?
> > It can save 12K on my platform,
> > My dtb is 164K
> 
> Yes, I've been thinking about this one. Unfortunately there is a conflict
> with another feature that I'm merging for v3.19. See commit 08d53aa5,
> "of/fdt: export fdt blob as /sys/firmware/fdt" in linux-next.
> That commit requires the original blob to be kept around.
> 
> In order to free the original dtb, the /sys/firmware/fdt feature will need
> to be changed to let it be configured out. All things considered, that is
> probably the right thing to do, but doing so increases the memory load for
> the platforms that want /sys/firmware/fdt. I'd like to see what the impact
> would be on the code to switch to this method when /sys/firmware/fdt is
> configured out.
> 
Oh, I understand,
If enable /sys/firmware/fdt feature patch, doesn't need 
My patch is fine,
So need 2 method to unflatten dtb blob.


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