Re: [RFC PATCH 6/6] powerpc/microwatt: Stop building the hash MMU code

Christophe Leroy [off-list ref] writes:

Le 27/08/2021 à 18:34, Nicholas Piggin a écrit :

quoted

Microwatt is radix-only, so stop selecting the hash MMU code.

This saves 20kB compressed dtbImage and 56kB vmlinux size.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
  arch/powerpc/configs/microwatt_defconfig | 1 -
  arch/powerpc/platforms/Kconfig.cputype   | 1 +
  arch/powerpc/platforms/microwatt/Kconfig | 1 -
  3 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/powerpc/configs/microwatt_defconfig b/arch/powerpc/configs/microwatt_defconfig
index bf5f2e5905eb..6fbad42f9e3d 100644
--- a/arch/powerpc/configs/microwatt_defconfig
+++ b/arch/powerpc/configs/microwatt_defconfig

@@ -26,7 +26,6 @@ CONFIG_PPC_MICROWATT=y
  # CONFIG_PPC_OF_BOOT_TRAMPOLINE is not set
  CONFIG_CPU_FREQ=y
  CONFIG_HZ_100=y
-# CONFIG_PPC_MEM_KEYS is not set
  # CONFIG_SECCOMP is not set
  # CONFIG_MQ_IOSCHED_KYBER is not set
  # CONFIG_COREDUMP is not set

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 9b90fc501ed4..b9acd6c68c81 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype

@@ -371,6 +371,7 @@ config SPE
  config PPC_64S_HASH_MMU
  	bool "Hash MMU Support"
  	depends on PPC_BOOK3S_64
+	depends on !PPC_MICROWATT

Do we really want to start nit picking which platforms can select such or such option ?
Isn't it enough to get it off through the defconfig ?

Is PPC_MICROWATT mutually exclusive with other book3s64 configs ? Don't we build multiplatform kernels ?

Yeah that belongs in the microwatt defconfig, not as a forced exclusion
in Kconfig.

cheers