On Wed, Mar 21, 2018 at 08:32:54PM -0400, Jerome Glisse wrote: > > I am testing with drivers/char/hmm_dmirror.c from your git repository. > > > > The addr I got (before "- size") is actually 0x7fffffffff, so equally > > (1 << 40). > > > > So from your reply, it seems to me that HMM is supposed to request a > > region like it. > > The dummy driver by default test the private memory, i had patches to > make it test public memory too somewhere in a branch. So yes this is > expected from the dummy driver. HMM here is trying to get a region that > will not collide with any known existing resources. Idealy we would > like a platform/arch function for that but it is hard to justify it > nor is there a safe way to find such thing either from arch/platform > specific code (there isn't for x86 at least). > > For real device driver of pcie devices, the advice is to use the pci > bar region of the device. This way we know for sure we do not collide > with anything (ie use hmm_devmem_add_resource() not hmm_devmem_add() > but this need some code change for res->desc).
I see. Thank you!
