On Thu, 26 Aug 2010 04:12:10 +0200 Michał Nazarewicz <m.nazarewicz@xxxxxxxxxxx> wrote: > On Thu, 26 Aug 2010 02:58:57 +0200, KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > > Hmm, you may not like this..but how about following kind of interface ? > > > > Now, memoyr hotplug supports following operation to free and _isolate_ > > memory region. > > # echo offline > /sys/devices/system/memory/memoryX/state > > > > Then, a region of memory will be isolated. (This succeeds if there are free > > memory.) > > > > Add a new interface. > > > > % echo offline > /sys/devices/system/memory/memoryX/state > > # extract memory from System RAM and make them invisible from buddy allocator. > > > > % echo cma > /sys/devices/system/memory/memoryX/state > > # move invisible memory to cma. > > At this point I need to say that I have no experience with hotplug memory but > I think that for this to make sense the regions of memory would have to be > smaller. Unless I'm misunderstanding something, the above would convert > a region of sizes in order of GiBs to use for CMA. > Now, x86's section size is == #ifdef CONFIG_X86_32 # ifdef CONFIG_X86_PAE # define SECTION_SIZE_BITS 29 # define MAX_PHYSADDR_BITS 36 # define MAX_PHYSMEM_BITS 36 # else # define SECTION_SIZE_BITS 26 # define MAX_PHYSADDR_BITS 32 # define MAX_PHYSMEM_BITS 32 # endif #else /* CONFIG_X86_32 */ # define SECTION_SIZE_BITS 27 /* matt - 128 is convenient right now */ # define MAX_PHYSADDR_BITS 44 # define MAX_PHYSMEM_BITS 46 #endif == 128MB...too big ? But it's depend on config. IBM's ppc guys used 16MB section, and recently, a new interface to shrink the number of /sys files are added, maybe usable. Something good with this approach will be you can create "cma" memory before installing driver. But yes, complicated and need some works. Bye, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>