On Wed, Jun 17, 2015 at 12:00:56AM +0200, Igor Mammedov wrote: > On Tue, 16 Jun 2015 23:14:20 +0200 > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > On Tue, Jun 16, 2015 at 06:33:37PM +0200, Igor Mammedov wrote: > > > since commit > > > 1d4e7e3 kvm: x86: increase user memory slots to 509 > > > > > > it became possible to use a bigger amount of memory > > > slots, which is used by memory hotplug for > > > registering hotplugged memory. > > > However QEMU crashes if it's used with more than ~60 > > > pc-dimm devices and vhost-net since host kernel > > > in module vhost-net refuses to accept more than 65 > > > memory regions. > > > > > > Increase VHOST_MEMORY_MAX_NREGIONS from 65 to 509 > > > > It was 64, not 65. > > > > > to match KVM_USER_MEM_SLOTS fixes issue for vhost-net. > > > > > > Signed-off-by: Igor Mammedov <imamm...@redhat.com> > > > > Still thinking about this: can you reorder this to > > be the last patch in the series please? > sure > > > > > Also - 509? > userspace memory slots in terms of KVM, I made it match > KVM's allotment of memory slots for userspace side.
Maybe KVM has its reasons for this #. I don't see why we need to match this exactly. > > I think if we are changing this, it'd be nice to > > create a way for userspace to discover the support > > and the # of regions supported. > That was my first idea before extending KVM's memslots > to teach kernel to tell qemu this number so that QEMU > at least would be able to check if new memory slot could > be added but I was redirected to a more simple solution > of just extending vs everdoing things. > Currently QEMU supports upto ~250 memslots so 509 > is about twice high we need it so it should work for near > future Yes but old kernels are still around. Would be nice if you can detect them. > but eventually we might still teach kernel and QEMU > to make things more robust. A new ioctl would be easy to add, I think it's a good idea generally. > > > > > > > --- > > > drivers/vhost/vhost.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > > > index 99931a0..6a18c92 100644 > > > --- a/drivers/vhost/vhost.c > > > +++ b/drivers/vhost/vhost.c > > > @@ -30,7 +30,7 @@ > > > #include "vhost.h" > > > > > > enum { > > > - VHOST_MEMORY_MAX_NREGIONS = 64, > > > + VHOST_MEMORY_MAX_NREGIONS = 509, > > > VHOST_MEMORY_F_LOG = 0x1, > > > }; > > > > > > -- > > > 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/