Re: [PATCH 1/1] numa: check mem or memdev in numa configuration

[Igor Mammedov <imammedo@redhat.com>]

On Thu, 17 Feb 2022 10:38:32 +0100
Li Zhang <lizhang@suse.de> wrote:

> On 2/17/22 10:10 AM, Igor Mammedov wrote:
> > On Wed, 16 Feb 2022 17:36:13 +0100
> > Li Zhang <lizhang@suse.de> wrote:
> >   
> >> If there is no mem or memdev in numa configuration, it always
> >> reports the error as the following:
> >>
> >> total memory for NUMA nodes (0x0) should equal RAM size (0x100000000)
> >>
> >> This error is confusing and the reason is that total memory of numa nodes
> >> is always 0 if there is no mem or memdev in numa configuration.
> >> So it's better to check mem or memdev in numa configuration.
> >>
> >> Signed-off-by: Li Zhang <lizhang@suse.de>
> >> ---
> >>   hw/core/numa.c | 5 +++++
> >>   1 file changed, 5 insertions(+)
> >>
> >> diff --git a/hw/core/numa.c b/hw/core/numa.c
> >> index 1aa05dcf42..11cbec51eb 100644
> >> --- a/hw/core/numa.c
> >> +++ b/hw/core/numa.c
> >> @@ -132,6 +132,11 @@ static void parse_numa_node(MachineState *ms, NumaNodeOptions *node,
> >>   
> >>       have_memdevs = have_memdevs ? : node->has_memdev;
> >>       have_mem = have_mem ? : node->has_mem;
> >> +    if (!node->has_memdev && !node->has_mem) {
> >> +        error_setg(errp, "numa configuration should use mem= or memdev= ");
> >> +        return;
> >> +    }  
> > 
> > Wouldn't this breaks memory less numa nodes?  
> 
> Yes, you are right. It will break it if there more numa nodes
> than memory, and the numa nodes have no memory backends specified.
> 
> Is it allowed for users to specify more numa nodes than memory?
yep, I think we support it at least for one of the targets
(but I don't remember which one(s))

> 
> > 
> > I'd rather add/rephrase to original error message that memory
> > should be specified explicitly for desired numa nodes.
> > And I'd not mention 'mem=' since
> >    docs/about/removed-features.rst:``-numa node,mem=...`` (removed in 5.1)  
> 
> Thanks for your suggestions, I will rephrase it.
> 
> >   
> >> +
> >>       if ((node->has_mem && have_memdevs) || (node->has_memdev && have_mem)) {
> >>           error_setg(errp, "numa configuration should use either mem= or memdev=,"
> >>                      "mixing both is not allowed");  
> >   
>