On Thu, Apr 18, 2024 at 11:54:15PM +0900, DaeRo Lee wrote: > 2024년 4월 17일 (수) 오후 3:03, Mike Rapoport <rppt@xxxxxxxxxx>님이 작성: > > > > On Tue, Apr 16, 2024 at 09:06:35PM +0900, skseofh@xxxxxxxxx wrote: > > > From: Daero Lee <daero_le.lee@xxxxxxxxxxx> > > > > > > Like reserved-memory with the 'no-map' property and only 'size' property > > > (w/o 'reg' property), there are memory regions need to be allocated in > > > memblock.memory marked with the MEMBLOCK_NOMAP flag, but should not be > > > allocated in memblock.reserved. > > > > This still does not explain why you need such regions. > > > > As Wei Yang explained, memblock does not allocate memory from > > memblock.reserved. The memblock.reserved array represents memory that is in > > use by firmware or by early kernel allocations and cannot be freed to page > > allocator. > Thank you for your comments. I used the wrong word. > When I use 'allocate', I mean that the region 'adds' to the memblock.reserved. > > > > > If you have a region that's _NOMAP in memblock.memory and is absent in > > memblock.reserved it will not be mapped by the kernel page tables, but it > > will be considered as free memory by the core mm. > > > > Is this really what you want? > If my understanding is right, before freeing (memory && !reserved) > area, we marked the memblock.reserved regions and memblock.memory > regions with no-map flag. And when we free (memory && !reserved) area, > we skip the memblock.memory regions with no-map(see > should_skip_region). So, I think that the memory regions with no-map > flag will not be considered as free memory. You are right here. But I still don't understand *why* do you want to change the way early_init_dt_alloc_reserved_memory_arch() works. > Regards, > DaeRo Lee -- Sincerely yours, Mike.
