Add some contents for vhost sample. Signed-off-by: Changchun Ouyang <changchun.ouyang at intel.com> --- doc/guides/sample_app_ug/vhost.rst | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)
diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst index fa53db6..756838c 100644 --- a/doc/guides/sample_app_ug/vhost.rst +++ b/doc/guides/sample_app_ug/vhost.rst @@ -654,6 +654,35 @@ The number of free hugepages can be checked as follows: The command above indicates how many hugepages are free to support QEMU's allocation request. +**Can user space VHOST work properly with the guest with 2M sized hug pages?** + +Yes, it can. The guest may have 2M or 1G sized huge pages file, the user space VHOST can work properly in both cases. + +**Can user space VHOST work with QEMU without '-mem-prealloc' option?** +The current implementation work properly only when the guest memory is pre-allocated, so you are required to use the +correct QEMU version(e.g. 1.6) which supports '-mem-prealloc'; And the option '-mem-prealloc' is required to be specified +explicitly in QEMU command line. + +**Can user space VHOST work with QEMU version without shared memory mapping?** +No, it can't, shared memory mapping is mandatory for user space VHOST to work properly with guest as user space VHOST +need access the shared memory from guest to receive and transmit packets. You are required to make sure the QEMU version +support shared memory mapping. + +**When using libvirt "virsh create" the qemu-wrap.py spawns a new process to run "qemu-kvm". This impacts the behavior +of the "virsh destroy" which kills the process running "qemu-wrap.py" without actually destroying the VM (leaves the +"qemu-kvm" process running).** +This patch can fix this issue: http://dpdk.org/ml/archives/dev/2014-June/003607.html + +**On Ubuntu environment, QEMU fail to start a new guest normally with user space VHOST due to hug pages can't be +allocated for the new guest.** +The solution for this issue could be adding "-boot c" into QEMU command line to make sure the huge pages are allocated +properly and then the guest startup normally. You may use "cat /proc/meminfo" to check if there is any change in value +of HugePages_Total and HugePages_Free after the guest startup. + +**Why I get this logging message: "eventfd_link: module verification failed: signature and/or required key missing - tainting kernel"?** +You can ignore the above logging message. The message occurs due to the new module eventfd_link is not a standard +module of Linux, but it is necessary for user space VHOST current implementation(CUSE-based) to communicate with guest. + Running DPDK in the Virtual Machine ----------------------------------- -- 1.8.4.2
