[PATCH] powerpc: Fix build failure when MEMORY_HOTPLUG=y

ARCH_ENABLE_MEMORY_HOTPLUG is enabled by default for powerpc. This causes build
failures when SPARSEMEM=n as memory hotplug needs definition which are defined
only when SPARSEMEM=y. The error is as follows:

arch/powerpc/platforms/pseries/hotplug-memory.c:27:31: error: 'SECTION_SIZE_BITS' undeclared (first use in this function)
arch/powerpc/platforms/pseries/hotplug-memory.c:27:31: note: each undeclared identifier is reported only once for each function it appears in
arch/powerpc/platforms/pseries/hotplug-memory.c: In function 'pseries_remove_memblock':
arch/powerpc/platforms/pseries/hotplug-memory.c:98:34: error: 'SECTION_SIZE_BITS' undeclared (first use in this function)
make[2]: *** [arch/powerpc/platforms/pseries/hotplug-memory.o] Error 1

Signed-off-by: Pranith Kumar <redacted>
CC: Andew Morton <akpm@linux-foundation.org>
---
 arch/powerpc/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9c1aa77..da16ffe 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -383,6 +383,7 @@ config ARCH_CPU_PROBE_RELEASE
 
 config ARCH_ENABLE_MEMORY_HOTPLUG
 	def_bool y
+	depends on SPARSEMEM
 
 config ARCH_HAS_WALK_MEMORY
 	def_bool y

-- 
1.9.1

On Tue, Aug 19, 2014 at 11:01 PM, Pranith Kumar [off-list ref] wrote:

In light of my investigation for your spufs patch, I guess this is a non-SMP
PSERIES config?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

On Wed, Aug 20, 2014 at 4:00 AM, Geert Uytterhoeven
[off-list ref] wrote:

quoted

1.9.1

In light of my investigation for your spufs patch, I guess this is a non-SMP
PSERIES config?

So what happens is SELECT_MEMORY_MODEL choses FLATMEM_MANUAL because
of which SPARSEMEM is not enabled despite having
ARCH_SPARSEMEM_ENABLE=y.

-- 
Pranith

On Tue, 2014-19-08 at 21:01:05 UTC, Pranith Kumar wrote:

ARCH_ENABLE_MEMORY_HOTPLUG is enabled by default for powerpc. This causes build
failures when SPARSEMEM=n as memory hotplug needs definition which are defined
only when SPARSEMEM=y. The error is as follows:

arch/powerpc/platforms/pseries/hotplug-memory.c:27:31: error: 'SECTION_SIZE_BITS' undeclared (first use in this function)
arch/powerpc/platforms/pseries/hotplug-memory.c:27:31: note: each undeclared identifier is reported only once for each function it appears in

I don't see how you can even build pseries without SPARSEMEM=y ?

The three options are:

	default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
	default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
	default FLATMEM_MANUAL

We don't have DISCONTIGMEM.

FLATMEM_MANUAL depends on !ARCH_SPARSEMEM_ENABLE.

We turn on ARCH_SPARSEMEM_ENABLE, and it's not user editable.

cheers