2024년 4월 27일 (토) 오후 5:50, Mike Rapoport <rppt@xxxxxxxxxx>님이 작성: > > On Fri, Apr 19, 2024 at 10:59:52AM +0900, DaeRo Lee wrote: > > 2024년 4월 19일 (금) 오전 10:46, DaeRo Lee <skseofh@xxxxxxxxx>님이 작성: > > > > > > In memmap_init_reserved_pages, we mark memblock.reserved as > > > PageReserved first and mark the memblock.reserved with nomap flag > > > also. > > Sorry. This is my mistake. 'memblock.memory with nomap flag' is right. > > > > > -> Isn't this duplicated work? (If we add no-map region to > > > memblock.reserved 'and' mark in memblock.memory..) > > > So, I think that for the no-map region, we don't need to add to the > > > memblock.reserved. > > > This is what we do now in early_init_dt_reserve_memory. the nomap > > > region is not added to the memblock.reserved. > > > > > > In early_init_dt_alloc_reserved_memory_arch, if 'nomap' is true, we > > > mark the memblock.memory region as _NOMAP. And if the return value > > > 'err' is not zero(which is '-ENOMEM' from memblock_isolate_range), we > > > free the region. > > > - 'nomap' is true -> memblock_mark_nomap : success -> not free the region > > > > > > : fail -> free the region > > > And it can be said that we add the region to the memblock.reserved > > > using memblock_phys_alloc_range and if the region is nomap, then we > > > can free the region from memblock.reserved. But is it necessary to add > > > it to memblock.reserved? We just need the region in memblock.memory to > > > mark nomap. > > > > > > So, here is what I think: > > > - reserved-memory w/ nomap region -> mark only to memblock.memory > > > - reserved-memory w/o nomap region -> add to the memblock.reserved > > NOMAP and memblock.reserved are semantically different, and at makes sense > to have a "reserved nomap" node in fdt recorded in both memblock.memory and > memblock.reserved. > > memblock.reserved represents the memory that is used by firmware or early > kernel allocation, so reserved memory in fdt should be reserved in memblock > as well. I believe it's an oversight that early_init_dt_reserve_memory() > does not call memblock_reserve() for nomap memory. > > NOMAP is a property of a memory region that says that that region should > not be mapped in the linear map, it's not necessarily in use. I agree that the NOMAP region should be added to memblock.reserved. So, I think we need to clean-up memmap_init_reserved_pages, because in this function we call reserve_bootmem_region for memblock.reserved and memblock.memory with nomap. We don't need to call reserve_bootmem_region for nomap. Regards,. DaeRo Lee
