On 6/30/26 2:18 PM, Gregory Price wrote: > Drivers which may pass hotplug policy down to DAX need MMOP_ symbols > and the mhp_get_default_online_type function for hotplug use cases. > > Some drivers (cxl) co-mingle their hotplug and devdax use-cases into > the same driver code, and chose the dax_kmem path as the default driver > path - making it difficult to require hotplug as a predicate to building > the overall driver (it may break other non-hotplug use-cases). > > Export mhp_get_default_online_type function to allow these drivers to > build when hotplug is disabled and still use the DAX use case. > > In the built-out case we simply return MMOP_OFFLINE as it's > non-destructive. The internal function can never return -1 either, > so we choose this to allow for defining the function with 'enum mmop'. > > Signed-off-by: Gregory Price <[email protected]> > Acked-by: David Hildenbrand (Arm) <[email protected]> Reviewed-by: Dave Jiang <[email protected]> > --- > include/linux/memory_hotplug.h | 2 ++ > mm/memory_hotplug.c | 1 + > 2 files changed, 3 insertions(+) > > diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h > index 5d4b628c4a1f..4d51fcb93a37 100644 > --- a/include/linux/memory_hotplug.h > +++ b/include/linux/memory_hotplug.h > @@ -317,6 +317,8 @@ extern struct zone *zone_for_pfn_range(enum mmop > online_type, > extern int arch_create_linear_mapping(int nid, u64 start, u64 size, > struct mhp_params *params); > void arch_remove_linear_mapping(u64 start, u64 size); > +#else > +static inline enum mmop mhp_get_default_online_type(void) { return > MMOP_OFFLINE; } > #endif /* CONFIG_MEMORY_HOTPLUG */ > > #endif /* __LINUX_MEMORY_HOTPLUG_H */ > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 6833208cc17c..494257054095 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -239,6 +239,7 @@ enum mmop mhp_get_default_online_type(void) > > return mhp_default_online_type; > } > +EXPORT_SYMBOL_GPL(mhp_get_default_online_type); > > void mhp_set_default_online_type(enum mmop online_type) > {
