Re: [PATCH v1 12/22] docs: driver-api: add .rst files from the main dir

Mauro Carvalho Chehab
2019-06-19T14:15:34Z

Hi David,

Em Wed, 19 Jun 2019 14:39:10 +0100
David Howells <dhowells@redhat.com> escreveu:

> Mauro Carvalho Chehab <mchehab+samsung@kernel.org> wrote:
>
> > > > -Documentation/nommu-mmap.rst
> > > > +Documentation/driver-api/nommu-mmap.rst
>
> Why is this moving to Documentation/driver-api?

Good point. I tried to do my best with those document renames, but
I'm pretty sure some of them ended by going to the wrong place - or
at least there are arguments in favor of moving it to different
places :-)

The driver-api ended to be where most of the stuff has been moved,
as this is the main kAPI dir (there is also a core-api dir for kAPI too).

I tend to place there stuff that has a mix of kAPI and uAPI at
driver-api, as usually such documents are written assuming that
the one that would be reading it is a Kernel developer.

> It's less to do with drivers
> than with the userspace mapping interface. Documentation/vm/ would seem a
> better home.
>
> Or should we institute a Documentation/uapi/? Though that might be seen to
> overlap with man2. Actually, should this be in man7?

Actually, there is an userspace-api dir too. While the logs show that
this was created back on 2017, I only noticed it very recently.

Re-checking the file, I see your point: there are lots of
userspace-relevant contents there. Yet, it also mentions kAPI internals,
like a reference for file and vm ops (at "Providing shareable character
device support" session):

file->f_op->get_unmapped_area()
file->f_op->mmap()
vm_ops->close()

It is up to MM people and Jon to decide where to place it.

In any case, the best (long term) seems to split it on separate files,
one with kAPI and another one with uAPI (just like may other subsystem
specific docs).

Thanks,
Mauro