Re: [libvirt] [PATCH] qemu: New XML to disable memory merge at guest startup

On 04/17/2013 08:22 AM, Osier Yang wrote: > QEMU introduced command line "-mem-merge=on|off" (defaults to on) to > enable/disable the memory merge (KSM) at guest startup. This exposes > it by new XML: > <memoryBacking> > <nosharepages/> > </memoryBacking> > > The XML tag is same with what we used internally for old RHEL. Good - that means that RHEL 6 (and any other downstream distro that was already borrowing the RHEL extension) will not break when rebasing to pick up this change from upstream in place of their downstream extension (RHEL will actually want to add a followup patch on top of this that _also_ tries the older -redhat-disable-KSM downstream spelling of the option, but that's a problem for RHEL and not this list).

> > + if (strstr(help, "-mem-merge")) > + virQEMUCapsSet(qemuCaps, QEMU_CAPS_MEM_MERGE); This would only scrape the existence of -mem-merge in qemu 1.2 and earlier, since we don't read -help in 1.3 and later. But qemu 1.2 doesn't have -mem-merge, so this bit will never get set. You need to instead populate the new capability based on a QMP probe, not string scraping. But I don't know offhand what that probe would be; you may need to ask on the qemu list.

Looking forward to v2.