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-rw-r--r--arch/x86/Kconfig.debug19
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index e46c214..b322f12 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -129,6 +129,25 @@ config DOUBLEFAULT
option saves about 4k and might cause you much additional grey
hair.
+config DEBUG_TLBFLUSH
+ bool "Set upper limit of TLB entries to flush one-by-one"
+ depends on DEBUG_KERNEL && (X86_64 || X86_INVLPG)
+ ---help---
+
+ X86-only for now.
+
+ This option allows the user to tune the amount of TLB entries the
+ kernel flushes one-by-one instead of doing a full TLB flush. In
+ certain situations, the former is cheaper. This is controlled by the
+ tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
+ to -1, the code flushes the whole TLB unconditionally. Otherwise,
+ for positive values of it, the kernel will use single TLB entry
+ invalidating instructions according to the following formula:
+
+ flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
+
+ If in doubt, say "N".
+
config IOMMU_DEBUG
bool "Enable IOMMU debugging"
depends on GART_IOMMU && DEBUG_KERNEL