diff options
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 95 | ||||
| -rw-r--r-- | init/main.c | 11 |
2 files changed, 94 insertions, 12 deletions
diff --git a/init/Kconfig b/init/Kconfig index 8a63c404ef4..f6281711166 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -924,6 +924,15 @@ config KMOD endif # MODULES +config INIT_ALL_POSSIBLE + bool + help + Back when each arch used to define their own cpu_online_map and + cpu_possible_map, some of them chose to initialize cpu_possible_map + with all 1s, and others with all 0s. When they were centralised, + it was better to provide this option than to break all the archs + and have several arch maintainers persuing me down dark alleys. + config STOP_MACHINE bool default y @@ -936,10 +945,90 @@ source "block/Kconfig" config PREEMPT_NOTIFIERS bool +choice + prompt "RCU Implementation" + default CLASSIC_RCU + config CLASSIC_RCU - def_bool !PREEMPT_RCU + bool "Classic RCU" help This option selects the classic RCU implementation that is designed for best read-side performance on non-realtime - systems. Classic RCU is the default. Note that the - PREEMPT_RCU symbol is used to select/deselect this option. + systems. + + Select this option if you are unsure. + +config TREE_RCU + bool "Tree-based hierarchical RCU" + help + This option selects the RCU implementation that is + designed for very large SMP system with hundreds or + thousands of CPUs. + +config PREEMPT_RCU + bool "Preemptible RCU" + depends on PREEMPT + help + This option reduces the latency of the kernel by making certain + RCU sections preemptible. Normally RCU code is non-preemptible, if + this option is selected then read-only RCU sections become + preemptible. This helps latency, but may expose bugs due to + now-naive assumptions about each RCU read-side critical section + remaining on a given CPU through its execution. + +endchoice + +config RCU_TRACE + bool "Enable tracing for RCU" + depends on TREE_RCU || PREEMPT_RCU + help + This option provides tracing in RCU which presents stats + in debugfs for debugging RCU implementation. + + Say Y here if you want to enable RCU tracing + Say N if you are unsure. + +config RCU_FANOUT + int "Tree-based hierarchical RCU fanout value" + range 2 64 if 64BIT + range 2 32 if !64BIT + depends on TREE_RCU + default 64 if 64BIT + default 32 if !64BIT + help + This option controls the fanout of hierarchical implementations + of RCU, allowing RCU to work efficiently on machines with + large numbers of CPUs. This value must be at least the cube + root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit + systems and up to 262,144 for 64-bit systems. + + Select a specific number if testing RCU itself. + Take the default if unsure. + +config RCU_FANOUT_EXACT + bool "Disable tree-based hierarchical RCU auto-balancing" + depends on TREE_RCU + default n + help + This option forces use of the exact RCU_FANOUT value specified, + regardless of imbalances in the hierarchy. This is useful for + testing RCU itself, and might one day be useful on systems with + strong NUMA behavior. + + Without RCU_FANOUT_EXACT, the code will balance the hierarchy. + + Say N if unsure. + +config TREE_RCU_TRACE + def_bool RCU_TRACE && TREE_RCU + select DEBUG_FS + help + This option provides tracing for the TREE_RCU implementation, + permitting Makefile to trivially select kernel/rcutree_trace.c. + +config PREEMPT_RCU_TRACE + def_bool RCU_TRACE && PREEMPT_RCU + select DEBUG_FS + help + This option provides tracing for the PREEMPT_RCU implementation, + permitting Makefile to trivially select kernel/rcupreempt_trace.c. diff --git a/init/main.c b/init/main.c index 17e9757bfde..ad8f9f53f8d 100644 --- a/init/main.c +++ b/init/main.c @@ -75,15 +75,6 @@ #include <asm/smp.h> #endif -/* - * This is one of the first .c files built. Error out early if we have compiler - * trouble. - */ - -#if __GNUC__ == 4 && __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ == 0 -#warning gcc-4.1.0 is known to miscompile the kernel. A different compiler version is recommended. -#endif - static int kernel_init(void *); extern void init_IRQ(void); @@ -604,6 +595,8 @@ asmlinkage void __init start_kernel(void) sort_main_extable(); trap_init(); rcu_init(); + /* init some links before init_ISA_irqs() */ + early_irq_init(); init_IRQ(); pidhash_init(); init_timers(); |