Re: [PATCH] docs/vm: add documentation of memory models

Randy Dunlap
2019-04-25T15:01:44Z

On 4/25/19 1:22 AM, Mike Rapoport wrote:
> Hi Randy,
>
> On Wed, Apr 24, 2019 at 06:08:46PM -0700, Randy Dunlap wrote:
>> On 4/24/19 3:28 AM, Mike Rapoport wrote:
>>> Describe what {FLAT,DISCONTIG,SPARSE}MEM are and how they manage to
>>> maintain pfn <-> struct page correspondence.
>>>
>>> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
>>> ---
>>> Documentation/vm/index.rst | 1 +
>>> Documentation/vm/memory-model.rst | 171 ++++++++++++++++++++++++++++++++++++++
>>> 2 files changed, 172 insertions(+)
>>> create mode 100644 Documentation/vm/memory-model.rst
>>>
>>
>> Hi Mike,
>> I have a few minor edits below...
>
> I kinda expected those ;-)
>
>>> diff --git a/Documentation/vm/memory-model.rst b/Documentation/vm/memory-model.rst
>>> new file mode 100644
>>> index 0000000..914c52a
>>> --- /dev/null
>>> +++ b/Documentation/vm/memory-model.rst
>
> ...
>
>>> +
>>> +With FLATMEM, the conversion between a PFN and the `struct page` is
>>> +straightforward: `PFN - ARCH_PFN_OFFSET` is an index to the
>>> +`mem_map` array.
>>> +
>>> +The `ARCH_PFN_OFFSET` defines the first page frame number for
>>> +systems that their physical memory does not start at 0.
>>
>> s/that/when/ ? Seems awkward as is.
>
> Yeah, it is awkward. How about
>
> The `ARCH_PFN_OFFSET` defines the first page frame number for
> systems with physical memory starting at address different from 0.

OK. Thanks.

>>> +
>>> +DISCONTIGMEM
>>> +============
>>> +
>>
>> thanks.
>> --
>> ~Randy
>>
>

--
~Randy