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When starting QEMU, or when hotplugging a PCI device QEMU might
lock some memory. How much? Well, that's an undecidable problem.
But despite that, we try to guess. And it more or less works,
until there's a counter example. This time, it's a guest with
both <hostdev/> and an NVMe <disk/>. I've started a simple guest
with 4GiB of memory:
# virsh dominfo fedora
Max memory: 4194304 KiB
Used memory: 4194304 KiB
And here are the amounts of memory that QEMU tried to lock,
obtained via:
grep VmLck /proc/$(pgrep qemu-kvm)/status
1) with just one <hostdev/>
VmLck: 4194308 kB
2) with just one NVMe <disk/>
VmLck: 4328544 kB
3) with one <hostdev/> and one NVMe <disk/>
VmLck: 8522852 kB
Now, what's surprising is case 2) where the locked memory exceeds
the VM memory. It almost resembles VDPA. Therefore, treat is as
such.
Unfortunately, I don't have a box with two or more spare NVMe-s
so I can't tell for sure. But setting limit too tight means QEMU
refuses to start.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2014030
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
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==============================
Libvirt API for virtualization
==============================
Libvirt provides a portable, long term stable C API for managing the
virtualization technologies provided by many operating systems. It
includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware
vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER
Hypervisor.
For some of these hypervisors, it provides a stateful management
daemon which runs on the virtualization host allowing access to the
API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other
languages including Python, Perl, PHP, Go, Java, OCaml, as well as
mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the
website:
https://libvirt.org
License
=======
The libvirt C API is distributed under the terms of GNU Lesser General
Public License, version 2.1 (or later). Some parts of the code that are
not part of the C library may have the more restrictive GNU General
Public License, version 2.0 (or later). See the files ``COPYING.LESSER``
and ``COPYING`` for full license terms & conditions.
Installation
============
Instructions on building and installing libvirt can be found on the website:
https://libvirt.org/compiling.html
Contributing
============
The libvirt project welcomes contributions in many ways. For most components
the best way to contribute is to send patches to the primary development
mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
=======
The libvirt project has two primary mailing lists:
* libvirt-users@redhat.com (**for user discussions**)
* libvir-list@redhat.com (**for development only**)
Further details on contacting the project are available on the website:
https://libvirt.org/contact.html