Re: [PATCH 0/2] RFC: add -mem-shared option

[Paolo Bonzini]

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.

Paolo