Re: [PATCH v2 8/9] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE

[David Hildenbrand]

On 05.03.21 16:42, Peter Xu wrote:
> On Fri, Mar 05, 2021 at 11:16:33AM +0100, David Hildenbrand wrote:
> > +#define OVERCOMMIT_MEMORY_PATH "/proc/sys/vm/overcommit_memory"
> > +static bool map_noreserve_effective(int fd, bool readonly, bool shared)
> > +{
>
> [...]
>
> > @@ -184,8 +251,7 @@ void *qemu_ram_mmap(int fd,
> >       size_t offset, total;
> >       void *ptr, *guardptr;
> >   
> > -    if (noreserve) {
> > -        error_report("Skipping reservation of swap space is not supported");
> > +    if (noreserve && !map_noreserve_effective(fd, shared, readonly)) {
>
> Need to switch "shared" & "readonly"?

Indeed, interestingly it has the same effect (as we don't have anonymous 
read-only memory in QEMU :) )

(wouldn't have happened with flags  ... hmm)

Thanks!

--
Thanks,

David / dhildenb