Re: [PATCH 00/12] Fixing TI Keystone2 kexec

[Dave Young <dyoung@redhat.com>]

On 05/11/16 at 09:52am, Russell King - ARM Linux wrote:
> On Wed, May 11, 2016 at 04:29:23PM +0800, Dave Young wrote:
> > Hi, Russell
> > 
> > On 04/28/16 at 10:26am, Russell King - ARM Linux wrote:
> > > These changes are required for TI Keystone2 kexec to be functional.  TI
> > > Keystone2 has the run-time view of physical memory above 4GiB, but with
> > > a boot time alias below 4GiB which can only be used during the early
> > > boot.
> > > 
> > > This means we need to translate run-time physical addresses (which the
> > > kernel uses) to boot-time physical addresses, which, having discussed
> > > with Eric, is what the kexec tools and kexec kernel API requires.
> > > 
> > > We publish a special set of boot time resources in /proc/iomem, which
> > > the (modified) kexec tools look for in preference to the normal resources.
> > > Hence, if these are found, the kexec tools make use of these resources,
> > > and thus kexec tools use the boot-time view of physical memory.
> > 
> > I think getting memory ranges from device tree will be better than
> > adding more stuff to /proc/iomem. Geoff's arm64 kexec patches is using dtb
> > you can refer to the patchset.
> 
> I think you're confusing things.  DT doesn't contain the boot alias
> memory ranges - it's not a separate chunk of memory.  It's an alias
> of the same physical address space found higher in the physical
> address range.

Hmm, if we forget about kexec how does the 1st kernel get boot memory?
not from DT?

> 
> If we put it in DT, then we need a way to also describe that it is an
> alias of some other bit of physical memory.

I may missed the background, I just want kexec to get infomation just like
the normal kernel.

> 
> -- 
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Thanks
Dave