On Fri, Jul 19, 2019 at 12:52:39PM +0200, Pavel Machek wrote: > On Thu 2019-07-18 22:57:48, Christoph Hellwig wrote: > > On Thu, Jul 18, 2019 at 06:32:53PM -0700, john.hubb...@gmail.com wrote: > > > + HMM_MIRROR provides a way to mirror ranges of the CPU page tables > > > + 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. > > > + > > > + Select HMM_MIRROR if you have hardware that meets the above > > > + description. An early, partial list of such hardware is: > > > + an NVIDIA GPU >= Pascal, Mellanox IB >= mlx5, or an AMD GPU. > > > > Nevermind that the Nvidia support is stagaging and looks rather broken, > > there is no Mellanox user of this either at this point. > > > > But either way this has no business in a common kconfig help. Just > > drop the fine grained details and leave it to the overview. > > I disagree here. This explains what kind of hardware this is for (very > new). Partial list does not hurt, and I know that I probably don't > need to enable this. > > How else am I supposed to know if my computer needs page tables > synchronized?
It is like MMU_NOTIFIERS, if something needs it, then it will select it. Maybe it should just be a hidden kconfig anyhow as there is no reason to turn it on without also turning on a using driver. Jason
