21 Oct
2020
21 Oct
'20
11:20 p.m.
On Wed, Oct 21, 2020 at 09:24:08PM +0200, Daniel Vetter wrote:
On Wed, Oct 21, 2020 at 6:37 PM Jason Gunthorpe jgg@ziepe.ca wrote:
On Wed, Oct 21, 2020 at 05:54:54PM +0200, Daniel Vetter wrote:
The trouble is that io_remap_pfn adjust vma->pgoff, so we'd need to split that. So ideally ->mmap would never set up any ptes.
/dev/mem makes pgoff == pfn so it doesn't get changed by remap.
pgoff doesn't get touched for MAP_SHARED either, so there are other users that could work like this - eg anyone mmaping IO memory is probably OK.
I was more generally thinking for io_remap_pfn_users because of the mkwrite use-case we might have in fbdev emulation in drm.
You have a use case for MAP_PRIVATE and io_remap_pfn_range()??
Jason