Re: [libvirt] [PATCH 1/2] conf: Forbid hugepages and <source type='file'/>
On 10/15/2018 03:17 PM, Daniel P. Berrangé wrote:
On Mon, Oct 15, 2018 at 02:39:26PM +0200, Michal Privoznik wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1633562
>
> Under <memoryBacking/> we allow users to configure various memory
> backing related knobs. However, there are some combinations that
> make no sense. For instance, requesting hugepages and file
> allocation at the same time. Forbid this configuration then.
The huge pages we allocate come from a file in /dev/hugepages,
so this description doesn't really make sense.
Sure, in the end the mmap() that qemu calls is a file somewhere under
/dev/hugepages (btw terrible, really terrible path for hugetlbfs mount
point because it suggests hugepages are devices).
But <source type='file'/> is usually used to put domain RAM under
/var/lib/libvirt/ram/.. (and to enforce memory-backing-file).
IIUC, what's actually happening is that you're trying to avoid
a historical bug.
More or less. This basically a result of 992bf863fcc.
Anyway, might as well do nothing on this front :-)
Michal