Re: [Qemu-ppc] KVM memory slots limit on powerpc

[Christian Borntraeger]

Am 04.09.2015 um 11:35 schrieb Thomas Huth:
> 
>  Hi all,
> 
> now that we get memory hotplugging for the spapr machine on qemu-ppc,
> too, it seems like we easily can hit the amount of KVM-internal memory
> slots now ("#define KVM_USER_MEM_SLOTS 32" in
> arch/powerpc/include/asm/kvm_host.h). For example, start
> qemu-system-ppc64 with a couple of "-device secondary-vga" and "-m
> 4G,slots=32,maxmem=40G" and then try to hot-plug all 32 DIMMs ... and
> you'll see that it aborts way earlier already.
> 
> The x86 code already increased the amount of KVM_USER_MEM_SLOTS to 509
> already (+3 internal slots = 512) ... maybe we should now increase the
> amount of slots on powerpc, too? Since we don't use internal slots on
> POWER, would 512 be a good value? Or would less be sufficient, too?

When you are at it, the s390 value should also be increased I guess.

Christian