[libvirt] [PATCH] nodeinfo: fix detection of physical memory on uclibc/musl libc

[Natanael Copa]

On Tue, 15 Apr 2014 10:37:40 +0100
"Daniel P. Berrange" <berrange at redhat.com> wrote:

> On Tue, Apr 15, 2014 at 11:31:23AM +0200, Natanael Copa wrote:
> > The gnulib's physmem_total will as a fallback report 64MB as total
> > memory if sysconf(_SC_PHYS_PAGES) is unimplemented on linux. This makes
> > it impossible to detect if physmem_total works or not, so we try first
> > the linux only sysinfo(2) before falling back to gnulibs physmem_total.
> > 
> > This makes the total memory be correctly reported on musl libc and
> > uclibc.
> > 
> > Signed-off-by: Natanael Copa <ncopa at alpinelinux.org>
> > ---
> >  configure.ac   |  2 +-
> >  src/nodeinfo.c | 22 ++++++++++++++++------
> >  2 files changed, 17 insertions(+), 7 deletions(-)
> 
> I think you should instead patch the gnulib physmem_total() function
> to support use of  sysinfo() itself. That way all the many users of
> GNULIB will work correctly on musl/uclibc, rather than just libvirt.

the intention was to fix all 3 places:

* fix libvirt not trust physmem_total
* fix gnulib to use sysinfo and fallback to sysconf
* add _SC_PHYS_PAGES support to musl libc

In any case, the gnulib's physmem_total will most likely always fall
back to 64MB instead of fail with error since it looks like thats the
way it is designed. I doubt they will accept fix for that.

That means that libvirt cannot really trust physmem_total and IMHO it
should be avoided.

The effective result is that you cannot create any vm with more than
64MB (MB not GB...) ram with virt-manager which I think is worse than
fail with error.

-nc