Re: [Qemu-devel] [RFC PATCH 6/9] pc: pass paravirt info for hotplug memory slots to BIOS

[Vasilis Liaskovitis]

On Fri, Apr 20, 2012 at 12:33:57PM +0200, Igor Mammedov wrote:
> On 04/19/2012 04:08 PM, Vasilis Liaskovitis wrote:
> >-    numa_fw_cfg = g_malloc0((1 + max_cpus + nb_numa_nodes) * 8);
> >+    numa_fw_cfg = g_malloc0((2 + max_cpus + nb_numa_nodes + 3 * 
> >nb_hp_memslots) * 8);
> >      numa_fw_cfg[0] = cpu_to_le64(nb_numa_nodes);
> >+    numa_fw_cfg[1] = cpu_to_le64(nb_hp_memslots);
> this will brake compatibility if guest was migrated from old->new qemu
> than on reboot it will use old bios that expects numa_fw_cfg[1] to be 
> something else.
> Could memslots info be moved to the end of an existing interface?

right. The number of memslots can be placed at 1 + max_cpus + nb_numa_nodes,
instead of right after the number of nodes. This way the old layout is 
preserved,
and all memslot info comes at the end. I will rewrite.

thanks,
- Vasilis