On Sat, May 11, 2019 at 08:39:12AM +1200, Michael Schmitz wrote:
Hi Mike,
thanks for addressing this longstanding issue!
Am 08.05.2019 um 22:09 schrieb Mike Rapoport:
Hi,
This is the first attempt to replace DISCONTIGMEM with SPARSEMEM on m68k
for systems with !SINGLE_MEMORY_CHUNK set.
With SPARSEMEM there is a single node for the entire physical memory and to
cope with holes in the physical address space it is divided to sections of
up to 16M.
Each section has it's own memory map which size depends on actual populated
memory.
I tested this using ARAnyM and it works both with kernel loaded to ST-RAM
(low address chunk) and FastRAM/TT-RAM (high address chunk).
I do wonder though - is the DMA memory pool reserved in
atari_stram_map_pages() (which was left unmapped previously if the kernel
was loaded to FastRAM, due to constraints of the discontigmem memory model)
considered already allocated now with sparsemem, and won't be used in
'normal'memory allocations?
The switch to sparse does not change this part. If the kernel is loaded in
ST-RAM, the code around sparse_init() makes sure that the memory map is
allocated from high physical addresses and then atari/stram.c is able to
reserve the frame buffer memory. If the kernel is loaded to FastRAM, the
ST-RAM remains unmapped as with discontigmem and the atari/stram.c maps it
as IOMEM.
I can't say I really understand the reason for inability to use ST-RAM as
normal memory if the kernel was loaded into the FastRAM, maybe with sprase
it would be easier to fix it.
Haven't seen any evidence to the contrary, but I've not put the system under
any kind of memory pressure.
With these caveats:
Tested-By: Michael Schmitz <schmitzmic@xxxxxxxxx>
Thanks!
Cheers,
Michael
The section size of 16M was chosen pretty much arbitrarily as I couldn't
find specs for systems with e.g. Zorro memory extensions.
Mike Rapoport (3):
m68k/mm: make node data and node setup depend on CONFIG_DISCONTIGMEM
m68k/mm: enable use of generic memory_model.h for !DISCONTIGMEM
m68k/mm: switch from DISCONTIGMEM to SPARSEMEM
arch/m68k/Kconfig.cpu | 12 +++++--
arch/m68k/include/asm/page.h | 2 ++
arch/m68k/include/asm/page_mm.h | 6 +++-
arch/m68k/include/asm/sparsemem.h | 8 +++++
arch/m68k/include/asm/virtconvert.h | 2 +-
arch/m68k/mm/init.c | 8 ++---
arch/m68k/mm/motorola.c | 64 ++++++++++++++++++++++++++++++-------
7 files changed, 83 insertions(+), 19 deletions(-)
create mode 100644 arch/m68k/include/asm/sparsemem.h
--
Sincerely yours,
Mike.
