Re: [PATCH v2 5/7] virtio-mem: s390 support

Heiko Carstens
2024-10-15T08:38:04Z

On Mon, Oct 14, 2024 at 09:16:45PM +0200, David Hildenbrand wrote:
> On 14.10.24 20:48, Heiko Carstens wrote:
> > On Mon, Oct 14, 2024 at 04:46:17PM +0200, David Hildenbrand wrote:
> > > to dump. Based on this, support for dumping virtio-mem memory can be
> > Hm.. who will add this support? This looks like a showstopper to me.
>
> The cover letter is clearer on that: "One remaining work item is kdump
> support for virtio-mem memory. This will be sent out separately once initial
> support landed."
>
> I had a prototype, but need to spend some time to clean it up -- or find
> someone to hand it over to clean it up.
>
> I have to chose wisely what I work on nowadays, and cannot spend that time
> if the basic support won't get ACKed.
>
> > Who is supposed to debug crash dumps where memory parts are missing?
>
> For many production use cases it certainly needs to exist.
>
> But note that virtio-mem can be used with ZONE_MOVABLE, in which case mostly
> only user data (e.g., pagecache,anon) ends up on hotplugged memory, that
> would get excluded from makedumpfile in the default configs either way.
>
> It's not uncommon to let kdump support be added later (e.g., AMD SNP
> variants).

I'll leave it up to kvm folks to decide if we need kdump support from
the beginning or if we are good with the current implementation.