[PATCH v4 05/14] kexec: Add Kexec HandOver (KHO) generation helpers

[Jason Gunthorpe]

On Mon, Feb 10, 2025 at 03:58:00PM -0500, Pasha Tatashin wrote:
> >
> > > +What:                /sys/kernel/kho/dt_max
> > > +Date:                December 2023
> > > +Contact:     Alexander Graf <graf at amazon.com>
> > > +Description:
> > > +             KHO needs to allocate a buffer for the DT that gets
> > > +             generated before it knows the final size. By default, it
> > > +             will allocate 10 MiB for it. You can write to this file
> > > +             to modify the size of that allocation.
> >
> > Seems gross, why can't it use a non-contiguous page list to generate
> > the FDT? :\
> 
> We will consider some of these ideas in the future version. I like the
> idea of using preserved memory to carry sparse KHO tree: i.e FDT over
> sparse memory, maybe use the anchor page to describe how it should be
> vmapped into a virtually contiguous tree in the next kernel?

Yeah, but this is now permanent uAPI that has to be kept forever. I
think you should not add this when there are enough ideas on how to
completely avoid it.

Jason