Messages in this thread | | | Subject | Re: [PATCH v4 09/10] powerpc/watchpoint: Return available watchpoints dynamically | From | Ravi Bangoria <> | Date | Tue, 21 Jul 2020 13:45:58 +0530 |
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>>>> @@ -46,7 +47,7 @@ struct arch_hw_breakpoint { >>>> >>>> static inline int nr_wp_slots(void) >>>> { >>>> - return HBP_NUM_MAX; >>>> + return cpu_has_feature(CPU_FTR_DAWR1) ? HBP_NUM_TWO : HBP_NUM_ONE; >>> So it'd be something like: >>> + return cpu_has_feature(CPU_FTR_DAWR1) ? HBP_NUM_MAX : 1; >>> But thinking that there might be more slots added in the future, it >>> may be better to make the number of slots a variable that is set >>> during the init and then have this function return that. >> >> Not sure I follow. What do you mean by setting number of slots a >> variable that is set during the init? > Sorry I was unclear there. > I was just looking and saw arm also has a variable number of hw breakpoints. > If we did something like how they handle it, it might look something like: > > static int num_wp_slots __ro_after_init; > > int nr_wp_slots(void) { > return num_wp_slots; > } > > static int __init arch_hw_breakpoint_init(void) { > num_wp_slots = work out how many wp_slots > } > arch_initcall(arch_hw_breakpoint_init); > > Then we wouldn't have to calculate everytime nr_wp_slots() is called. > In the future if more wp's are added nr_wp_slots() will get more complicated. > But just an idea, feel free to ignore.
Ok I got the idea. But ARM arch_hw_breakpoint_init() is much more complex compared to our nr_wp_slots(). I don't see any benefit by making our code like ARM.
Thanks for the idea though :) Ravi
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