Re: [PATCH v3 0/3] m68k/mm: switch from DISCONTIGMEM to SPARSEMEM

[Michael Schmitz <schmitzmic@gmail.com>]

Hi Mike,

Sorry, I had seen those but didn't get around to test in time.

Applying your patch series to Geert's v5.9-rc1, I get this:

>   CC      kernel/bounds.s
>   CC      arch/m68k/kernel/asm-offsets.s
> In file included from ./include/linux/mmzone.h:19,
>                  from ./include/linux/topology.h:33,
>                  from ./include/linux/irq.h:19,
>                  from ./include/asm-generic/hardirq.h:13,
>                  from ./arch/m68k/include/generated/asm/hardirq.h:1,
>                  from ./include/linux/hardirq.h:10,
>                  from ./include/linux/interrupt.h:11,
>                  from ./include/linux/kernel_stat.h:9,
>                  from arch/m68k/kernel/asm-offsets.c:16:
> ./include/linux/page-flags-layout.h:28:10: fatal error: 
> asm/sparsemem.h: No such file or directory
>  #include <asm/sparsemem.h>
>           ^~~~~~~~~~~~~~~~~
> compilation terminated.
> make[2]: *** [arch/m68k/kernel/asm-offsets.s] Error 1
> make[1]: *** [prepare0] Error 2
> make: *** [__sub-make] Error 2

Your patch announcement blurb hat sparsemem.h listed among the changed 
files, but none of the three patches stats reference that file. Am I 
missing a prerequisite here?

Cheers,

     Michael


On 21/08/20 4:03 AM, Mike Rapoport wrote:
> Gentle ping :)
>
> On Sat, Jul 18, 2020 at 07:26:48PM +0300, Mike Rapoport wrote:
>> From: Mike Rapoport <rppt@linux.ibm.com>
>>
>> Hi,
>>
>> It took me a while to get back to this, but better late than never :)
>>
>> These patches 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
>> several megabytes.
>>
>> Each section has it's own memory map which size depends on actual populated
>> memory.
>>
>> The section size of 16M was chosen pretty much arbitrarily as I couldn't
>> find specs for systems with e.g. Zorro memory extensions.
>> Yet, we cannot use smaller sections and still be able to address the entire
>> 4G of the physical memory because the section number is encoded in the page
>> flags and there are only 8 bits available.
>>
>> For systems with several small memory chunks and with small (several megs)
>> holes between them, 16M section size would cause wasted parts in the memory
>> map and it is desirable to allow smaller section size at the expense of
>> limiting the addressable memory.
>>
>> I've hesitated between adding Kconfig option as Finn suggested [1] and
>> other options like SPARSE_VMEMMAP or ARCH_HAS_HOLES_MEMORYMODEL. In the
>> end, I think Kconfig is the simplest one from the implementation point of
>> view and would work fine for people that run mainline kernels on vintage
>> hardware.
>>
>> For the systems with ST-RAM and FastRAM, the switch to SPARSEMEM does not
>> change the limitation that if the kernel is loaded into the FastRam the
>> ST-RAM remains unmapped. It only ensures that if the kernel is loaded in
>> ST-RAM, 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.
>>
>> [1] https://marc.info/?l=linux-m68k&m=156309170500921&w=2
>>
>> v3 changes:
>> * rebase on the current upstream
>> * alias ARCH_PFN_BASE to m68k_memory[0].addr
>> * add configuration option to allow two variants of section size.
>>
>> v2 changes:
>> * rebase on the current upstream
>> * make ColdFire MMU select SINGLE_MEMORY_CHUNK in Kconfig.cpu
>>
>> 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               | 14 ++++++--
>>   arch/m68k/include/asm/page.h        |  2 ++
>>   arch/m68k/include/asm/page_mm.h     |  6 +++-
>>   arch/m68k/include/asm/q.h   |  8 +++++
>>   arch/m68k/include/asm/virtconvert.h |  2 +-
>>   arch/m68k/mm/init.c                 |  8 ++---
>>   arch/m68k/mm/motorola.c             | 64 ++++++++++++++++++++++++++++++-------
>>   7 files changed, 84 insertions(+), 20 deletions(-)
>>   create mode 100644 arch/m68k/include/asm/sparsemem.h
>>
>> -- 
>> 2.7.4
>>
>>
>> *** BLURB HERE ***
>>
>> 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               | 23 ++++++++++++++---
>>   arch/m68k/include/asm/page.h        |  2 ++
>>   arch/m68k/include/asm/page_mm.h     |  7 +++++-
>>   arch/m68k/include/asm/virtconvert.h |  2 +-
>>   arch/m68k/mm/init.c                 |  8 +++---
>>   arch/m68k/mm/motorola.c             | 39 ++++++++++++++++++++++++++---
>>   6 files changed, 69 insertions(+), 12 deletions(-)
>>
>> -- 
>> 2.26.2
>>