Re: [PATCH v2 16/16] powerpc/microwatt: Don't select the hash MMU code

Excerpts from Joel Stanley's message of October 21, 2021 3:19 pm:

On Thu, 21 Oct 2021 at 04:04, Nicholas Piggin [off-list ref] wrote:

quoted

Microwatt is radix-only, so it does not require hash MMU support.

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/microwatt/Kconfig | 1 -
 2 files changed, 2 deletions(-)

diff --git a/arch/powerpc/configs/microwatt_defconfig b/arch/powerpc/configs/microwatt_defconfig
index 6e62966730d3..7c8eb29d8afe 100644
--- a/arch/powerpc/configs/microwatt_defconfig
+++ b/arch/powerpc/configs/microwatt_defconfig

@@ -27,7 +27,6 @@ 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

We still end up with CONFIG_PPC_64S_HASH_MMU=y in the config as it
defaults to y.

If you make microwatt_defconfig? Hm, IIRC this came from savedefconfig 
after unselecting hash mmu so I'm not sure why that doesn't work.

We should disable in the defconfig it so your new changes are tested
by that defconfig:

+# CONFIG_PPC_64S_HASH_MMU is not set

I boot tested your series on Microwatt with microwatt_defconfig (with
and without that option set) and ppc64le_defconfig.

Nice.

Thanks,
Nick

Cheers,

Joel

quoted

diff --git a/arch/powerpc/platforms/microwatt/Kconfig b/arch/powerpc/platforms/microwatt/Kconfig
index 823192e9d38a..5e320f49583a 100644
--- a/arch/powerpc/platforms/microwatt/Kconfig
+++ b/arch/powerpc/platforms/microwatt/Kconfig

@@ -5,7 +5,6 @@ config PPC_MICROWATT
        select PPC_XICS
        select PPC_ICS_NATIVE
        select PPC_ICP_NATIVE
-       select PPC_HASH_MMU_NATIVE if PPC_64S_HASH_MMU
        select PPC_UDBG_16550
        select ARCH_RANDOM
        help
--

2.23.0