On Wed, 2007-10-31 at 14:28 +0900, KAMEZAWA Hiroyuki wrote: > On Tue, 30 Oct 2007 11:19:11 -0800 > Badari Pulavarty <[EMAIL PROTECTED]> wrote: > > > Hi KAME, > > > > As I mentioned while ago, ppc64 does not export information about > > "system RAM" in /proc/iomem. Looking at the code and usage > > scenerios I am not sure what its really serving. Could you > > explain what its purpose & how the range can be invalid ? > > > Hm, I added walk_memory_resource() for hot-add, at first. > > Size of memory section is fixed and just depend on architecture, but > any machine can have any memory-hole within continuous memory-section-size > range of physical memory. Then we have to detect which page can be > target of online_page() and which are leaved as Reserved. > > ioresource was good structure for remembering "which memory is conventional > memory" and i386/x86_64/ia64 registered conventional memory as "System RAM", > when I posted patch. (just say "System Ram" is not for memory hotplug.) > > I used walk_memory_resource() again in memory hotremove.
Agreed. On PPC64, within a memblock represented in /sysfs are pretty small (16MB) and there can not be any holes. And you can add/remove memory only on 16MB multiple chunks. > > (If I rememember correctly, walk_memory_resouce() helps x86_64 memory hot-add. > than our ia64 box. > In our ia64 box, we do node-hotadd. Section size is 1GiB and it has some > "for firmware" area in newly-added node.) > > > At least on ppc64, all the memory ranges we get passed comes from > > /sysfs memblock information and they are guaranteed to match > > device-tree entries. On ppc64, each 16MB chunk has a /sysfs entry > > and it will be part of the /proc/device-tree entry. Since we do > > "online" or "offline" to /sysfs entries to add/remove pages - > > these ranges are guaranteed to be valid. > > > ok. > > > Since this check is redundant for ppc64, I propose following patch. > > Is this acceptable ? If some one really really wants, I can code > > up this to walk lmb or /proc/device-tree and verify the range & > > adjust the entries for overlap (I don't see how that can happen). > > > ok. If ppc64 guarantees "there is no memory hole in section", please try. > I have no objection. > I just would like to ask to add some text to explain > "ppc64 doesn't need to care memory hole in a section." Yes. I would like to go with this approach, rather than adding the information to /proc/iomem (as per Paul's suggestion). If I find cases where sections (16MB) *could* contain holes -OR- overlaps - I can easily add code to verify against lmb/proc-device-tree information easily without affecting arch-neutral code. Thanks, Badari _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
