Subject: Re: [Cbe-oss-dev] [PATCH] Ignore memory listed in PS3 device tree

From: Geoff Levand <[email-masked]>
Date: Tue, 03 Apr 2007 16:58:14 -0700

Arnd Bergmann wrote:
> On Wednesday 04 April 2007, Geoff Levand wrote:
>> So there are really two answers, one is that having the boot memory in the
>> DT hasn't changed, I just haven't finished that part yet. �The other is that
>> we get the amount of memory at runtime because it is a dynamic resource, and
>> cannot be known at DT compile time.
> 
> But the device tree can easily be modified before entering the new kernel,
> when the kboot kernel allocates all the memory it can get, it just needs
> to list it in the device tree in some preallocated device node.

Yes, but boot mem is not allocated by the guest, it is allocated by the policy
module.  The guest can only query how much boot mem has been allocated for
it.  This can be done by the bootloader, or the kernel itself, if done early
enough.  That info needs to be added to the DT before the kernel sets up its
boot mem structures.  My current plan is to do it in the bootloader, since
there is not a platform hook in the current powerpc arch code that is early
enough.

But you seem to say we can do something in the first stage kernel and pass
some info to the second stage kernel?  The trouble with that is that when
the kernel is used as a first stage, where does the info come from?  I want
to have a single kernel that can be either programmed into flash or loaded
by kexec.  For that to work the DT setup must be done in the wrapper, or
the kernel itself.

-Geoff