On Thu, Jul 11, 2013 at 2:24 AM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Wed, Jul 10, 2013 at 09:00:33PM -0400, Jerome Glisse wrote: >> On Wed, Jul 10, 2013 at 8:27 PM, Jean-Sébastien Pédron >> <jean-sebastien.pedron@xxxxxxxxxxx> wrote: >> > Hello, >> > >> > I'm trying to understand how TTM buffer object mapping works on Linux, to >> > make this behave properly on FreeBSD. >> > >> > Here's what I think I understand: >> > >> > When a buffer object is mmap()'d, ttm_bo_vm_open() is called. When there's a >> > page fault, the page is looked up and inserted in the VMA using >> > vm_insert_mixed(). When a buffer object is munmap()'d, ttm_bo_vm_close() is >> > called, which drops a reference. When the last reference is dropped, the >> > buffer object is destroyed. >> > >> > What's still not clear to me is how munmap() works here. After talking about >> > this on IRC with some people, I think that unmap_mapping_range() (called by >> > ttm_bo_unmap_virtual_locked()) is equivalent to calling munmap() from >> > userland. Is that true? >> >> Yes that's true. > > Afaik unmap_mapping_range only kills the ptes and doesn't remove the vma. > So not equivalent to a munmap from userspace. It simply allows us to > intercept the next access in the page fault handler and move the buffer > back into place. > -Daniel Yes, i was talking from a page point of view, ie page no longer have mapping and can be free. Cheers, Jerome _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
