Red Hat Bugzilla – Bug 1118707
VMstate static checker: backport -dump-vmstate feature to export json-encoded vmstate info
Last modified: 2015-03-05 03:10:45 EST
Description of problem: The static checker is merged usptream; backport it for 7.1. This will be useful to get vmstate json output and check for migration compatibility between various versions of qemu. Syntax is: qemu-kvm -dump-vmstate -M <machine type> -dump-vmstate <filename> Later, from the qemu sources, ./scripts/vmstate-static-checker.py -s src.json -d dest.json will output any migration-breaking changes introduced in dest.json as compared with src.json.
More info on invocation from upstream commit messages: For qemu: migration: dump vmstate info as a json file for static analysis This commit adds a new command, '-dump-vmstate', that takes a filename as an argument. When executed, QEMU will dump the vmstate information for the machine type it's invoked with to the file, and quit. The JSON-format output can then be used to compare the vmstate info for different QEMU versions, specifically to test whether live migration would break due to changes in the vmstate data. A Python script that compares the output of such JSON dumps is included in the following commit. and the script: vmstate-static-checker: script to validate vmstate changes This script compares the vmstate dumps in JSON format as output by QEMU with the -dump-vmstate option. It flags various errors, like version mismatch, sections going away, size mismatches, etc. This script is tolerant of a few changes that do not change the on-wire format, like embedding a few fields within substructs. The script takes -s/--src and -d/--dest parameters, to which filenames are given as arguments. Example: (in a qemu 2.0 tree): ./x86_64-softmmu/qemu-system-x86_64 -dump-vmstate qemu-2.0.json (in a qemu 2.2 tree:) ./x86_64-softmmu/qemu-system-x86_64 -dump-vmstate -M pc-i440fx-2.0 \ qemu-2.2-m2.0.json ./scripts/vmstate-static-checker.py -s qemu-2.0.json -d qemu-2.2-m2.0.json The script also takes a --reverse parameter to switch the src and dest jsons. This is just a shorthand for reversing the src and dest. The --help parameter shows usage information.
Fix included in qemu-kvm-1.5.3-67.el7
Verified on qemu-kvm-rhev-2.1.2-3.el7.x86_64: # /usr/libexec/qemu-kvm -M pc-q35-rhel7.1.0 -dump-vmstate pc-q35-rhel7.1.0 # cat pc-q35-rhel7.1.0 | head -n 20 { "vmschkmachine": { "Name": "pc-q35-rhel7.1.0" }, "usb-host": { "Name": "usb-host", "version_id": 1, "minimum_version_id": 1, "Description": { "name": "usb-host", "version_id": 1, "minimum_version_id": 1, "Fields": [ { "field": "parent_obj", "version_id": 0, "field_exists": false, "size": 5808, "Description": { "name": "USBDevice", ... Verified on qemu-kvm-1.5.3-75.el7.x86_64: # /usr/libexec/qemu-kvm -M pc-q35-rhel7.0.0 -dump-vmstate pc-q35-rhel7.0.0 # cat pc-q35-rhel7.0.0 | head -n 20 { "vmschkmachine": { "Name": "pc-q35-rhel7.0.0" }, "port92": { "Name": "port92", "version_id": 1, "minimum_version_id": 1, "Description": { "name": "port92", "version_id": 1, "minimum_version_id": 1, "Fields": [ { "field": "outport", "version_id": 0, "field_exists": false, "size": 1 } ]
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://rhn.redhat.com/errata/RHSA-2015-0349.html