[PATCH v4 0/8] MMU disabling code and kexec fixes

[Nicolas Pitre]

On Wed, 24 Aug 2011, Will Deacon wrote:

> On Wed, Aug 24, 2011 at 03:53:44PM +0100, Nicolas Pitre wrote:
> > On Wed, 24 Aug 2011, Will Deacon wrote:
> > > On top of that, I'd like to use the bottom of this page as a holding pen
> > > for secondary CPUs when doing an SMP kexec. In this case, the new kernel
> > > needs to take care not to allocate the page for general use. I suppose we
> > > could fix this with a new ATAG / FDT property but that seems a bit overkill.
> > 
> > Is it?
> 
> Well it means re-encoding a DT blob from within the kernel so that we can
> tell the next kernel not to allocate from a given page of physical memory.
> If we already have this infrastructure, then great, but it looks to me like
> it only lives within dtc (as libfdt) at the moment.

Hmmm... The kexec user space tools know how to manipulate a device tree 
for the next kernel, right?  So it's only a matter for it to ask the 
current kernel what the physical address for that page is and stuff it 
into the FDT it is preparing already.


Nicolas