On 20/03/2017 12:30, Daniel P. Berrange wrote:
> On Mon, Mar 20, 2017 at 12:24:26PM +0100, Laurent Vivier wrote:
>> Since commit 224245b ("spapr: Add LMB DR connectors"), NUMA node
>> memory size must be aligned to 256MB (SPAPR_MEMORY_BLOCK_SIZE).
>
> That commit only enabled the feature for the pseries-2.5 machine type
> several releases back now...
>
>> But when "-numa" option is provided without "mem" parameter,
>> the memory is equally divided between nodes, but 8MB aligned.
>> This can be not valid for pseries.
>>
>> In that case we can have:
>> $ ./ppc64-softmmu/qemu-system-ppc64 -m 4G -numa node -numa node -numa node
>> qemu-system-ppc64: Node 0 memory size 0x55000000 is not aligned to 256 MiB
>>
>> With this patch, we have:
>> (qemu) info numa
>> 3 nodes
>> node 0 cpus: 0
>> node 0 size: 1280 MB
>> node 1 cpus:
>> node 1 size: 1280 MB
>> node 2 cpus:
>> node 2 size: 1536 MB
>>
>> Signed-off-by: Laurent Vivier <lviv...@redhat.com>
>> ---
>> dtc | 2 +-
>> numa.c | 14 +++++++++-----
>> 2 files changed, 10 insertions(+), 6 deletions(-)
>>
>> diff --git a/dtc b/dtc
>> index 558cd81..fa8bc7f 160000
>> --- a/dtc
>> +++ b/dtc
>> @@ -1 +1 @@
>> -Subproject commit 558cd81bdd432769b59bff01240c44f82cfb1a9d
>> +Subproject commit fa8bc7f928ac25f23532afc8beb2073efc8fb063
>
> This looks unrelated
>
>> diff --git a/numa.c b/numa.c
>> index e01cb54..a911284 100644
>> --- a/numa.c
>> +++ b/numa.c
>> @@ -337,15 +337,19 @@ void parse_numa_opts(MachineClass *mc)
>> }
>> if (i == nb_numa_nodes) {
>> uint64_t usedmem = 0;
>> -
>> - /* On Linux, each node's border has to be 8MB aligned,
>> - * the final node gets the rest.
>> - */
>> +#if defined(TARGET_PPC64)
>> + /* pseries requests each node's border has to be 256 MB aligned
>> */
>> + const uint64_t numa_mem_align_mask = ~((1 << 28UL) - 1);
>> +#else
>
> but here you're forcing 256 MB alignement for all machine types. This is
> surely breaking machine ABI compat for anyone who previously used -numa
> with QEMU and upgrades to new QEMU expecting the same ABI.
Yes, you're right. I'm going to fix that...
Thanks,
Laurent
