[POWERPC] Enable CONFIG_FORCE_MAX_ZONEORDER for all PowerPC, and make selectable
This enables the FORCE_MAX_ZONEORDER Kconfig option for all PowerPC
systems. Previously, it was enabled only for 64-bit systems. We also
make the option selectable from the menu, so that the user can specify
different values. This is useful for 32-bit systems that need to
allocate more than 4MB of physically contiguous memory.
Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index f43d82d..625342e 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -211,14 +211,25 @@
source kernel/Kconfig.preempt
source "fs/Kconfig.binfmt"
-# We optimistically allocate largepages from the VM, so make the limit
-# large enough (16MB). This badly named config option is actually
-# max order + 1
config FORCE_MAX_ZONEORDER
- int
- depends on PPC64
+ int "Maximum zone order"
default "9" if PPC_64K_PAGES
- default "13"
+ default "13" if PPC64
+ default "11"
+ help
+ The kernel memory allocator divides physically contiguous memory
+ blocks into "zones", where each zone is a power of two number of
+ pages. This option selects the largest power of two that the kernel
+ keeps in the memory allocator. If you need to allocate very large
+ blocks of physically contiguous memory, then you may need to
+ increase this value.
+
+ This config option is actually maximum order plus one. For example,
+ a value of 11 means that the largest free memory block is 2^10 pages.
+
+ The page size is not necessarily 4KB. For example, on 64-bit
+ systems, 64KB pages can be enabled via CONFIG_PPC_64K_PAGES. Keep
+ this in mind when choosing a value for this option.
config HUGETLB_PAGE_SIZE_VARIABLE
bool
