• Andi Kleen's avatar
    [PATCH] x86_64: Reserve SRAT hotadd memory on x86-64 · 68a3a7fe
    Andi Kleen authored
    From: Keith Mannthey, Andi Kleen
    
    Implement memory hotadd without sparsemem. The memory in the SRAT
    hotadd area is just preserved instead and can be activated later.
    
    There are a few restrictions:
    - Only one continuous hotadd area allowed per node
    
    The main problem is dealing with the many buggy SRAT tables
    that are out there. The strategy here is to reject anything
    suspicious.
    
    Originally from Keith Mannthey, with several hacks and changes by AK
    and also contributions from Andrew Morton
    
    [ TBD: Problems pointed out by KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>:
    
     1) Goto's rebuild_zonelist patch will not work if CONFIG_MEMORY_HOTPLUG=n.
    
        Rebuilding zonelist is necessary when the system has just memory <
        4G at boot, and hot add memory > 4G.  because x86_64 has DMA32,
        ZONE_NORAML is not included into zonelist at boot time if system
        doesn't have memory >4G at boot.
    
        [AK: should just force the higher zones at boot time when SRAT tells us]
    
     2) zone and node's spanned_pages and present_pages are not incremented.
        They should be.
    
        For example, our server (ia64/Fujitsu PrimeQuest) can equip memory
        from 4G to 1T(maybe 2T in future), and SRAT will *always* say we have
        possible 1T +memory.  (Microsoft requires "write all possible memory
        in SRAT") When we reserve memmap for possible 1T memory, Linux will
        not work well in +minimum 4G configuraion ;)
    
        [AK: needs limiting to 5-10% of max memory]
     ]
    Signed-off-by: default avatarAndi Kleen <ak@suse.de>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    68a3a7fe
init.c 20 KB