Hi Michal, >> + * Maps a temporary range of memory with attributes `flags`; if the range is > Why do you always mention 'temporary' in the context of these functions? What > prevents us from using them to map a region for a longer period of time? > Also, temporary range is a bit confusing term and should better be replaced > with > 'Maps temporarily a range of memory ...' The intended meaning of ’temporary’ in the context of these functions is that the mapping is created, used, and then destroyed in a sequence e.g. where map_domain_page and unmap_domain_page are used. The term transient is possibly more fitting than temporary, and this is the term used in xen/common/page_alloc.c. Nothing actually prevents us from using them to map a region for a longer period of time, it is just that the intended use of the API is for transient mapping. Regarding the confusing comment - noted I will fix this in the next version of the series.
>> + * already mapped with the same attributes, including an inclusive match, >> the >> + * existing mapping is returned. This API is intended for mappings that >> exist > What are the use cases you want to cover to try to map the same range with the > same attributes more than once (without unmapping in the meantime)? The use case here is some places where a memory region is requested that has already been mapped, so we want to simply return the mapping. For example when the fdt is relocated in start_xen this uses a call to `xmalloc`, which eventually calls `map_domain_page` for an address in the static heap which has already been mapped. >> + * transiently for a short period between calls to this function and >> + * `unmap_mm_range`. >> + * >> + * @param start Base address of the range to map (inclusive). >> + * @param end Limit address of the range to map (exclusive). >> + * @param flags Flags for the memory range to map. >> + * @return Pointer to start of region on success, NULL on error. >> + */ >> +void *map_mm_range(paddr_t start, paddr_t end, unsigned int flags); > So far, all the MPU related functions use [base, limit) instead of [start, > end). > Do we see the benefit of diverging here? > > ~Michal Noted, I will align this to use [base, limit) in the next version of the series. Many thanks, Hari
