From: Will Deacon will.deacon@arm.com
commit 1b907f46db07405b6676addb91b32c546d772fcd upstream.
Having the instruction emulation submenu underneath "platform selection" is a great way to hide options we don't want people to use, but somewhat confusing when you stumble across it there.
Move the menuconfig option underneath "kernel features", where it makes a bit more sense.
Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: David Brown david.brown@linaro.org --- arch/arm64/Kconfig | 106 ++++++++++++++++++++++++++--------------------------- 1 file changed, 52 insertions(+), 54 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index b62bf4c..4c79862 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -166,60 +166,6 @@ config ARCH_XGENE help This enables support for AppliedMicro X-Gene SOC Family
-comment "Processor Features" - -menuconfig ARMV8_DEPRECATED - bool "Emulate deprecated/obsolete ARMv8 instructions" - depends on COMPAT - help - Legacy software support may require certain instructions - that have been deprecated or obsoleted in the architecture. - - Enable this config to enable selective emulation of these - features. - - If unsure, say Y - -if ARMV8_DEPRECATED - -config SWP_EMULATION - bool "Emulate SWP/SWPB instructions" - help - ARMv8 obsoletes the use of A32 SWP/SWPB instructions such that - they are always undefined. Say Y here to enable software - emulation of these instructions for userspace using LDXR/STXR. - - In some older versions of glibc [<=2.8] SWP is used during futex - trylock() operations with the assumption that the code will not - be preempted. This invalid assumption may be more likely to fail - with SWP emulation enabled, leading to deadlock of the user - application. - - NOTE: when accessing uncached shared regions, LDXR/STXR rely - on an external transaction monitoring block called a global - monitor to maintain update atomicity. If your system does not - implement a global monitor, this option can cause programs that - perform SWP operations to uncached memory to deadlock. - - If unsure, say Y - -config CP15_BARRIER_EMULATION - bool "Emulate CP15 Barrier instructions" - help - The CP15 barrier instructions - CP15ISB, CP15DSB, and - CP15DMB - are deprecated in ARMv8 (and ARMv7). It is - strongly recommended to use the ISB, DSB, and DMB - instructions instead. - - Say Y here to enable software emulation of these - instructions for AArch32 userspace code. When this option is - enabled, CP15 barrier usage is traced which can help - identify software that needs updating. - - If unsure, say Y - -endif - endmenu
menu "Bus support" @@ -548,6 +494,58 @@ config FORCE_MAX_ZONEORDER default "14" if (ARM64_64K_PAGES && TRANSPARENT_HUGEPAGE) default "11"
+menuconfig ARMV8_DEPRECATED + bool "Emulate deprecated/obsolete ARMv8 instructions" + depends on COMPAT + help + Legacy software support may require certain instructions + that have been deprecated or obsoleted in the architecture. + + Enable this config to enable selective emulation of these + features. + + If unsure, say Y + +if ARMV8_DEPRECATED + +config SWP_EMULATION + bool "Emulate SWP/SWPB instructions" + help + ARMv8 obsoletes the use of A32 SWP/SWPB instructions such that + they are always undefined. Say Y here to enable software + emulation of these instructions for userspace using LDXR/STXR. + + In some older versions of glibc [<=2.8] SWP is used during futex + trylock() operations with the assumption that the code will not + be preempted. This invalid assumption may be more likely to fail + with SWP emulation enabled, leading to deadlock of the user + application. + + NOTE: when accessing uncached shared regions, LDXR/STXR rely + on an external transaction monitoring block called a global + monitor to maintain update atomicity. If your system does not + implement a global monitor, this option can cause programs that + perform SWP operations to uncached memory to deadlock. + + If unsure, say Y + +config CP15_BARRIER_EMULATION + bool "Emulate CP15 Barrier instructions" + help + The CP15 barrier instructions - CP15ISB, CP15DSB, and + CP15DMB - are deprecated in ARMv8 (and ARMv7). It is + strongly recommended to use the ISB, DSB, and DMB + instructions instead. + + Say Y here to enable software emulation of these + instructions for AArch32 userspace code. When this option is + enabled, CP15 barrier usage is traced which can help + identify software that needs updating. + + If unsure, say Y + +endif + endmenu
menu "Boot options"