From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Huth <thuth@redhat.com>
Date: Fri, 04 Sep 2015 09:35:56 +0000
Subject: KVM memory slots limit on powerpc
Message-Id: <55E965FC.8080909@redhat.com>
List-Id: <kvm-ppc.vger.kernel.org>
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To: kvm-ppc@vger.kernel.org, qemu-ppc@nongnu.org, kvm@vger.kernel.org
Cc: Alex Williamson <alex.williamson@redhat.com>, David Gibson <dgibson@redhat.com>, Bharata B Rao <bharata@linux.vnet.ibm.com>


 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,slots2,maxmem@G" 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?

 Thomas