ARM: disallow pre-ARMv5 builds with ld.lld

lld cannot build for ARMv4/v4T targets because it inserts 'blx' instructions
that are unsupported there:

  ld.lld: warning: lld uses blx instruction, no object with architecture supporting feature detected

Add a Kconfig time dependency to prevent those targets from being
selected in randconfig builds.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://github.com/llvm/llvm-project/issues/50764
Link: https://github.com/ClangBuiltLinux/linux/issues/964
Link: https://lore.kernel.org/r/20221215162635.3750763-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a08c9d0..349af93 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -342,12 +342,14 @@ comment "CPU Core family selection"
 config ARCH_MULTI_V4
        bool "ARMv4 based platforms (FA526, StrongARM)"
        depends on !ARCH_MULTI_V6_V7
+       depends on !LD_IS_LLD
        select ARCH_MULTI_V4_V5
        select CPU_FA526 if !(CPU_SA110 || CPU_SA1100)
 
 config ARCH_MULTI_V4T
        bool "ARMv4T based platforms (ARM720T, ARM920T, ...)"
        depends on !ARCH_MULTI_V6_V7
+       depends on !LD_IS_LLD
        select ARCH_MULTI_V4_V5
        select CPU_ARM920T if !(CPU_ARM7TDMI || CPU_ARM720T || \
                CPU_ARM740T || CPU_ARM9TDMI || CPU_ARM922T || \