Hi Mike! Op ma 2 dec. 2019 om 17:01 schreef Mike Rapoport <rppt@xxxxxxxxxxxxx>:
The patches are here: https://www.spinics.net/lists/linux-m68k/msg13588.html Aside from some technicalities we had troubles deciding what should be the section size. With larger section size we might end up with wasted memory for memory maps and with smaller section size we'll have to limit the addressable physical memory...
I read through that thread. I believe our current page->flags needs 22 bits for the normal FLAGS and 2 bits for the ZONES, which leaves 8 bits for the SECTION. This is what Geert found out (it worked with MAX_PHYSMEM_BITS = 30 and SECTION_SIZE_BITS = 22). I think we can reduces ZONES to a single bit. We currently put all memory in ZONE_DMA, so I think we might just as well put it in ZONE_NORMAL and disable ZONE_DMA. That would enable us to have 8 MB sections and use the full 32-bit address space, correct? That may be a working compromise? Kind regards, Kars.
