From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [Cbe-oss-dev] [PATCH] Ignore memory listed in PS3 device tree From: Benjamin Herrenschmidt To: Geoff Levand In-Reply-To: <4612D8FE.1070400@am.sony.com> References: <1175208237.3122.78.camel@pmac.infradead.org> <26babf7b7398794f08e7417377b3facc@kernel.crashing.org> <1175473220.3144.1.camel@concordia.ozlabs.ibm.com> <432af8a0f928491e7d376923829f40a0@kernel.crashing.org> <1175568133.16182.15.camel@concordia <4612C48F.9080805@am.sony.com> <1175636904.10567.8.camel@shinybook.infradead.org> <4612D8FE.1070400@am.sony.com> Content-Type: text/plain Date: Wed, 04 Apr 2007 11:30:45 +1000 Message-Id: <1175650246.30879.41.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev list , nhorman@redhat.com, David Woodhouse , cbe-oss-dev , Ben Collins List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > There are several points here I feel need explanation. One is that memory > is a dynamic resource allocated by the HV, so it needs to be managed as a > dynamic resource by the guest OS. That happens on pSeries too and we still keep the device-tree in check, but that's related to the way all hotplug operations work on p... on these, the HV provides us with device-tree updates. I still think that the RMO is _not_ a dynamic resource, and as such should be present in the memory node as this is expected of quite a few things around including kexec tools. > Another point is that the HV has two > types of memory; boot memory, and virtual memory. Boot memory is what will > be in is in the DT when I finish the zImage implementation. Virtual memory > is what I currently have as hotplug memory. > > 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. It is just by some luck that the 2.6.16 > kernel continues to work correctly on the PS3, but it is not guaranteed to, > and has a good chance of failing on non-ps3 systems that use the lv1 hypervisor. Adding/removing memory outside of the RMO without updating the DT is fine with me. The RMO itself should be in the DT though. Ben.