Re: [PATCH RFC 0/3] MAP_POPULATE for device memory

On Mon, Mar 07, 2022 at 07:56:53AM -0800, Christoph Hellwig wrote:

On Mon, Mar 07, 2022 at 03:29:35PM +0200, Jarkko Sakkinen wrote:

...

So what would you suggest to sort out the issue? I'm happy to go with ioctl if nothing else is acceptable.

PLenty of drivers treat all mmaps as if MAP_POPULATE was specified, typically by using (io_)remap_pfn_range. If there any reason to only optionally have the pre-fault semantics for sgx? If not this should be really simple. And if we have a real need for it to be optional we'll just need to find a sane way to pass that information to ->mmap.

Dave, what if mmap() would just unconditionally EAUG after initialization?

It's an option, yes.

BR, Jarkko