On 29/11/19 10:39, Daniel P. Berrangé wrote: > On Fri, Nov 29, 2019 at 10:33:39AM +0100, Paolo Bonzini wrote: >> On 29/11/19 10:27, Daniel P. Berrangé wrote: >>>> Yes, with a fallback path currently using a temporary file under /tmp >>>> (we may want to use shm_open() instead, or a different location such >>>> as XDG_RUNTIME_DIR? - and use O_TMPFILE) >>> We can't assume either /tmp or XDG_RUNTIME_DIR is on tmpfs as that is no >>> where near standard across all OS distros, and even if on tmpfs these >>> dirs can be size limited to a significant subset of available RAM. IOW >>> we can't safely use them unless explicitly told to. >> >> Agreed, mkstemp+shm_open seems better. Perhaps this could be done in >> hostmem-memfd.c though, basically as a fallback option? In principle >> one could even use getmntent to search for a hugetlbfs mount. > > With mkstemp you still need to pick a location, and I don't think it > is clear there is a reliable choice that will always work.
Sorry, I meant mktemp (which is almost never the right choice so my brain fat-fingered it...) + shm_open(O_CREAT|O_EXCL). Paolo