Re: [Lhms-devel] Re: [PATCH] ACPI based Memory Hotplug Driver Patch

[Joel Schopp <jschopp-V7BBcbaFuwjMbYB6QlFGEg@public.gmane.org>]

> Although, I do wonder if we can have memory laid out in the firmware/
> directory in some kind of firmware-agnostic way.  
> 
> What I want is to make sure that any hotplug memory application that is
> written can use the same directories no matter whether it is a ppc
> machine using OpenFirmware or an x86/ia64 machine using ACPI.  

Noble goal, here is what we represent on ppc64 for a logical memory block.

bigbirdlp2:/proc/device-tree # ls ./memory\@10000000/
.  ..  device_type  ibm,my-drc-index  linux,phandle  name  reg
bigbirdlp2:/proc/device-tree/memory@10000000 # xxd ./reg
0000000: 0000 0000 1000 0000 0000 0000 1000 0000  ................
bigbirdlp2:/proc/device-tree/memory@10000000 # cat ./device_type
memory
bigbirdlp2:/proc/device-tree/memory@10000000 # xxd ./ibm,my-drc-index
0000000: 0000 0001                                ....
bigbirdlp2:/proc/device-tree/memory@10000000 # cat name
memory

I'm pretty sure the reg property is just a starting address, size pair. 
  The device type and name are pretty boring.  The drc-index is not 
guaranteed to correspond to anything (though it usually is start address 
/ size), you could call it arch-identifier or something.

> 
> Instead of just laying thing out in firmware/acpi, can we have another
> directory that mirrors this information in the system/devices/
> directory, but is identical across architectures?  

I'd do something like this for each LMB:

start-addr
size
arch-identifier


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