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

[Igor Mammedov <imammedo@redhat.com>]

On Fri, 29 Nov 2019 10:33:39 +0100
Paolo Bonzini <pbonzini@redhat.com> 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.

So far fall backs proved to be a pain to deal with, as end users can't
be sure what machine they are getting eventually.
I'd prefer if we fail cleanly if asked config isn't possible and
let user fix vm configuration instead.

> Paolo
> 
>