Am 28.11.2017 um 10:46 schrieb Jan Beulich:
On 28.11.17 at 10:12, <christian.koenig@xxxxxxx> wrote:
In theory the BIOS would search for address space and won't find
anything, so the hotplug operation should fail even before it reaches
the kernel in the first place.
How would the BIOS know what the OS does or plans to do?
As far as I know the ACPI BIOS should work directly with the register
content.
So when we update the register content to enable the MMIO decoding the
BIOS should know that as well.
I think
it's the other way around - the OS needs to avoid using any regions
for MMIO which are marked as hotpluggable in SRAT.
I was under the impression that this is exactly what
acpi_numa_memory_affinity_init() does.
Since there is
no vNUMA yet for Xen Dom0, that would need special handling.
I think that the problem is rather that SRAT is NUMA specific and if I'm
not totally mistaken the content is ignored when NUMA support isn't
compiled into the kernel.
When Xen steals some memory from Dom0 by hocking up itself into the e820
call then I would say the cleanest way is to report this memory in e820
as reserved as well. But take that with a grain of salt, I'm seriously
not a Xen expert.
Regards,
Christian.
Jan
