Re: HMM_MIRROR has less than useful help text

[Pavel Machek <pavel@ucw.cz>]

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On Thu 2019-07-18 07:25:42, Dan Williams wrote:
> On Thu, Jul 18, 2019 at 4:04 AM Balbir Singh <bsingharora@gmail.com> wrote:
> >
> > On Wed, Jul 17, 2019 at 5:41 PM Pavel Machek <pavel@ucw.cz> wrote:
> > >
> > > Hi!
> > >
> > > Commit c0b124054f9e42eb6da545a10fe9122a7d7c3f72 has very nice commit
> > > message, explaining what HMM_MIRROR is and when it is
> > > needed. Unfortunately, it did not make it into Kconfig help:
> > >
> > > CONFIG_HMM_MIRROR:
> > >
> > > Select HMM_MIRROR if you want to mirror range of the CPU page table of
> > > a
> > > process into a device page table. Here, mirror means "keep
> > > synchronized".
> > > Prerequisites: the device must provide the ability to write-protect
> > > its
> > > page tables (at PAGE_SIZE granularity), and must be able to recover
> > > from
> > > the resulting potential page faults.
> > >
> > > Could that be fixed?
> > >
> > > This is key information for me:
> > >
> > > # This is a heterogeneous memory management (HMM) process address space
> > > # mirroring.
> > > # This is useful for NVidia GPU >= Pascal, Mellanox IB >= mlx5 and more
> > > # hardware in the future.
> > >
> >
> > That seems like a reasonable request
> 
> Hi Pavel, care to send a patch?

I hoped patch author would fix up their code. I'm not HMM expert, he
should be...

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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