Re: [PATCH v4 09/10] powerpc/watchpoint: Return available watchpoints dynamically

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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