Messages in this thread |  | | From | Kars de Jong <> | Date | Wed, 4 Dec 2019 12:58:59 +0100 | Subject | Re: m68k Kconfig warning |
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Hi Mike!
Op ma 2 dec. 2019 om 17:01 schreef Mike Rapoport <rppt@linux.ibm.com>: > 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.
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