+config SELECT_MEMORY_MODEL
+ def_bool y
+ depends on EXPERIMENTAL || ARCH_SELECT_MEMORY_MODEL
+
choice
prompt "Memory model"
- default FLATMEM
- default SPARSEMEM if ARCH_SPARSEMEM_DEFAULT
- default DISCONTIGMEM if ARCH_DISCONTIGMEM_DEFAULT
+ depends on SELECT_MEMORY_MODEL
+ default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
+ default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
+ default FLATMEM_MANUAL
-config FLATMEM
+config FLATMEM_MANUAL
bool "Flat Memory"
depends on !ARCH_DISCONTIGMEM_ENABLE || ARCH_FLATMEM_ENABLE
help
only have one option here: FLATMEM. This is normal
and a correct option.
- If unsure, choose this option over any other.
+ Some users of more advanced features like NUMA and
+ memory hotplug may have different options here.
+ DISCONTIGMEM is an more mature, better tested system,
+ but is incompatible with memory hotplug and may suffer
+ decreased performance over SPARSEMEM. If unsure between
+ "Sparse Memory" and "Discontiguous Memory", choose
+ "Discontiguous Memory".
-config DISCONTIGMEM
+ If unsure, choose this option (Flat Memory) over any other.
+
+config DISCONTIGMEM_MANUAL
bool "Discontigious Memory"
depends on ARCH_DISCONTIGMEM_ENABLE
help
+ This option provides enhanced support for discontiguous
+ memory systems, over FLATMEM. These systems have holes
+ in their physical address spaces, and this option provides
+ more efficient handling of these holes. However, the vast
+ majority of hardware has quite flat address spaces, and
+ can have degraded performance from extra overhead that
+ this option imposes.
+
+ Many NUMA configurations will have this as the only option.
+
If unsure, choose "Flat Memory" over this option.
+config SPARSEMEM_MANUAL
+ bool "Sparse Memory"
+ depends on ARCH_SPARSEMEM_ENABLE
+ help
+ This will be the only option for some systems, including
+ memory hotplug systems. This is normal.
+
+ For many other systems, this will be an alternative to
+ "Discontigious Memory". This option provides some potential
+ performance benefits, along with decreased code complexity,
+ but it is newer, and more experimental.
+
+ If unsure, choose "Discontiguous Memory" or "Flat Memory"
+ over this option.
+
endchoice
+config DISCONTIGMEM
+ def_bool y
+ depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
+
+config SPARSEMEM
+ def_bool y
+ depends on SPARSEMEM_MANUAL
+
+config FLATMEM
+ def_bool y
+ depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
+
+config FLAT_NODE_MEM_MAP
+ def_bool y
+ depends on !SPARSEMEM
+
#
# Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's
# to represent different areas of memory. This variable allows
config NEED_MULTIPLE_NODES
def_bool y
depends on DISCONTIGMEM || NUMA
+
+config HAVE_MEMORY_PRESENT
+ def_bool y
+ depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
+
+#
+# SPARSEMEM_EXTREME (which is the default) does some bootmem
+# allocations when memory_present() is called. If this can not
+# be done on your architecture, select this option. However,
+# statically allocating the mem_section[] array can potentially
+# consume vast quantities of .bss, so be careful.
+#
+# This option will also potentially produce smaller runtime code
+# with gcc 3.4 and later.
+#
+config SPARSEMEM_STATIC
+ def_bool n
+
+#
+# Architectecture platforms which require a two level mem_section in SPARSEMEM
+# must select this option. This is usually for architecture platforms with
+# an extremely sparse physical address space.
+#
+config SPARSEMEM_EXTREME
+ def_bool y
+ depends on SPARSEMEM && !SPARSEMEM_STATIC