Re: [Qemu-devel] [PATCH] spapr: ensure we have at least one XICS server

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, May 13, 2015 at 12:29:33PM +0200, Greg Kurz wrote:
> XICS needs to know the upper value for cpu_index as it is used to compute
> the number of servers:
> 
>     smp_cpus * kvmppc_smt_threads() / smp_threads
> 
> When passing -smp cpus=1,threads=9 on a POWER8 host, we end up with:
> 
>     1 * 8 / 9 = 0
> 
> ... which leads to an assertion in both emulated:
> 
> Number of servers needs to be greater 0
> Aborted (core dumped)
> 
> ... and in-kernel XICS:
> 
> xics_kvm_realize: Assertion `icp->nr_servers' failed.
> Aborted (core dumped)
> 
> With this patch, we are sure that nr_servers > 0. Passing the same bogus
> -smp option then leads to:
> 
> qemu-system-ppc64: Cannot support more than 8 threads on PPC with KVM
> 
> ... which is a lot more explicit than the XICS errors.
> 
> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>

Looks sensible, thanks.

Applied to spapr-next branch.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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