linux-kernel - [RFC PATCH v1 06/19] powerpc/32s: Allow deselecting CONFIG_PPC

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Date:   Wed, 12 Aug 2020 12:05:57 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, ldv@...linux.org,
        viro@...iv.linux.org.uk
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [RFC PATCH v1 06/19] powerpc/32s: Allow deselecting CONFIG_PPC_FPU on
 mpc832x

The e300c2 core which is embedded in mpc832x CPU doesn't have
an FPU.

Make it possible to not select CONFIG_PPC_FPU when building a
kernel dedicated to that target.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/platforms/Kconfig.cputype | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 40ffcdba42b8..d4fd109f177e 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -32,7 +32,7 @@ choice
 config PPC_BOOK3S_6xx
 	bool "512x/52xx/6xx/7xx/74xx/82xx/83xx/86xx except 601"
 	select PPC_BOOK3S_32
-	select PPC_FPU
+	imply PPC_FPU
 	select PPC_HAVE_PMU_SUPPORT
 	select PPC_HAVE_KUEP
 	select PPC_HAVE_KUAP
@@ -229,9 +229,16 @@ config PPC_FPU_REGS
 	bool
 
 config PPC_FPU
-	bool
+	bool "Support for Floating Point Unit (FPU)" if PPC_MPC832x
 	default y if PPC64
 	select PPC_FPU_REGS
+	help
+	  This must be enabled to support the Floating Point Unit
+	  Most 6xx have an FPU but e300c2 core (mpc832x) don't have
+	  an FPU, so when building an embedded kernel for that target
+	  you can disable FPU support.
+
+	  If unsure say Y.
 
 config FSL_EMB_PERFMON
 	bool "Freescale Embedded Perfmon"
-- 
2.25.0