November 2010 - Devel - libvirt List Archives

[libvirt] [PATCH 5/7] Read the host sysinfo for the QEmu driver
by Daniel Veillard 03 Nov '10

03 Nov '10

Read and store the data when initializing the driver. Signed-off-by: Daniel Veillard <veillard(a)redhat.com> --- src/qemu/qemu_conf.h | 2 ++ src/qemu/qemu_driver.c | 7 +++++++ 2 files changed, 9 insertions(+), 0 deletions(-)

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[libvirt] [PATCH 3/7] Add smbios element to schema and configuration
by Daniel Veillard 03 Nov '10

03 Nov '10

the element has a mode attribute allowing only 3 values: - emulate: use the smbios emulation from the hypervisor - host: try to use the smbios values from the node - sysinfo: grab the values from the <sysinfo> fields * docs/schemas/domain.rng: extend the schemas * src/conf/domain_conf.h: add the flag to the domain config * src/conf/domain_conf.h: parse and serialize the smbios if present Signed-off-by: Daniel Veillard <veillard(a)redhat.com> --- docs/schemas/domain.rng | 16 ++++++++++++++++ src/conf/domain_conf.c | 17 +++++++++++++++++ src/conf/domain_conf.h | 11 +++++++++++ 3 files changed, 44 insertions(+), 0 deletions(-)

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[libvirt] Allow nbd-backed disk images?
by Adam Litke 03 Nov '10

03 Nov '10

I am trying to use a qcow image with libvirt where the backing 'file' is a qemu-nbd server. Unfortunately the security code assumes that backingStore is always a real file so something like 'nbd:0:3333' is rejected because a file with that name cannot be accessed. A simple patch like the following works around the problem -- are there any suggestions on how to do this properly? Note that I am not worried about directly using nbd images. That would require a new disk type with XML markup, etc. I only want it to be permitted as a backingStore. diff --git a/src/util/storage_file.c b/src/util/storage_file.c index 6f48b10..7c0ea9a 100644 --- a/src/util/storage_file.c +++ b/src/util/storage_file.c @@ -292,6 +292,13 @@ qcowXGetBackingStore(char **res, return BACKING_STORE_INVALID; if (size + 1 == 0) return BACKING_STORE_INVALID; + + /* Short-circuit nbd backing files */ + if (size >= 4 && STRPREFIX((const char *)(buf + offset), "nbd:")) { + return BACKING_STORE_OK; + } + if (VIR_ALLOC_N(*res, size + 1) < 0) { virReportOOMError(); return BACKING_STORE_ERROR; -- Thanks, Adam

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[libvirt] [PATCH v2] macvtap: libvirtd forgot macvtap device name during a shutdown/restart cycle
by Stefan Berger 03 Nov '10

03 Nov '10

V2: - removed change from virDomainNetDefFormat. The reported problem also does not occur. During a shutdown/restart cycle libvirtd forgot the macvtap device name that it had created on behalf of a VM so that a stale macvtap device remained on the host when the VM terminated. Libvirtd has to actively tear down a macvtap device and it uses its name for identifying which device to tear down. The solution is to not blank out the <target dev='...'/> completely, but only blank it out on VMs that are not active. So, if a VM is active, the device name makes it into the XML and is also being parsed. If a VM is not active, the device name is discarded. Signed-off-by: Stefan Berger <stefanb(a)us.ibm.com> --- src/conf/domain_conf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) Index: libvirt-acl/src/conf/domain_conf.c =================================================================== --- libvirt-acl.orig/src/conf/domain_conf.c +++ libvirt-acl/src/conf/domain_conf.c @@ -2343,7 +2343,8 @@ virDomainNetDefParseXML(virCapsPtr caps, def->data.direct.linkdev = dev; dev = NULL; - VIR_FREE(ifname); + if ((flags & VIR_DOMAIN_XML_INACTIVE)) + VIR_FREE(ifname); break;

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[libvirt] [PATCH] tests: fix daemon-conf testing failure
by Osier Yang 03 Nov '10

03 Nov '10

libvirtd.conf uses "libvirt" as the value of "unix_sock_group", however, group "libvirt" may not exist on system, in this case the case will always be failed, which will cause 'make check' , and 'make rpm' always be failed further more. As a solution, replace "libvirt" with "root" in "tmp.conf". * tests/daemon-conf --- tests/daemon-conf | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/tests/daemon-conf b/tests/daemon-conf index 6c91d96..225f84c 100755 --- a/tests/daemon-conf +++ b/tests/daemon-conf @@ -25,6 +25,9 @@ grep -v '\"PARAMETER = VALUE\"' "$conf" | grep '[a-z_] *= *[^ ]' | grep -vE '^ # Start with the sample libvirtd.conf file, uncommenting all real directives. sed -n 's/^#$[^ #]$/\1/p' "$conf" > tmp.conf +sed -e 's/^$unix_sock_group =$.*/\1 "root"/g' tmp.conf > k +mv k tmp.conf + # Iterate through that list of directives, corrupting one RHS at a # time and running libvirtd with the resulting config. Each libvirtd # invocation must fail. -- 1.7.2.3

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[libvirt] PCI/USB devices documentation
by Zdenek Styblik 03 Nov '10

03 Nov '10

Hello, so far unsuccessfully, I'm trying to attach PCI/USB devices to Guests (via virt-manager, soon via virsh because - whatever :]). Anyway, there is <hostdev managed='yes'> where I'm wondering what 'managed' means, because it's not documented here[1]. Is it a bug or is it documented elsewhere? btw also, 'Node devices XML format'[2] page is empty Thanks, Zdenek References: --- [1] http://libvirt.org/formatdomain.html#elementsUSB [2] http://libvirt.org/formatnode.html PS: I haven't forgotten about Slackware SSH how-to, but- *sigh* I promise! -- Zdenek Styblik Net/Linux admin OS TurnovFree.net email: stybla(a)turnovfree.net jabber: stybla(a)jabber.turnovfree.net

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[libvirt] [PATCH] Fix virPipeReadUntilEOF on more than 1024 bytes of data
by Daniel Veillard 03 Nov '10

03 Nov '10

This is a bug I found while testing the smbios support, it uses virPipeReadUntilEOF to read the stdout of the exec'ed dmidecode process and this failed to capture the full output. It read only 1024 bytes. The problem is that this is based on a poll loop, and in the loop we read at most 1024 bytes per filedescriptor, but we also note in the loop if poll indicates that the process won't output more than that on that fd by setting finished[i] = 1. The simplest way is that if we read a full buffer make sure finished[i] is still 0 because we will need another pass in the loop. Daniel diff --git a/src/util/util.c b/src/util/util.c index f7c7d32..a059675 100644 --- a/src/util/util.c +++ b/src/util/util.c @@ -984,6 +984,9 @@ virPipeReadUntilEOF(int outfd, int errfd, got = read(fds[i].fd, data, sizeof(data)); + if (got == sizeof(data)) + finished[i] = 0; + if (got == 0) { finished[i] = 1; continue; -- Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/ daniel(a)veillard.com | Rpmfind RPM search engine http://rpmfind.net/ http://veillard.com/ | virtualization library http://libvirt.org/

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[libvirt] Changing the default for qcow2 creation
by Matthew Booth 03 Nov '10

03 Nov '10

I've recently been investigating a severe performance issue I noticed when writing to a qcow2-backed image. When virt-v2v is doing a format conversion from raw to qcow2, it does the following: 1. Create a new qcow2 image 2. Launch a libguestfs appliance (kvm) using the new image 3. Write the source raw data to the appliance's block device I noticed that the same process writing to a raw image rather than a qcow2 image was adequately fast, and decided to do some testing. I've attached my simple test program.[1] It does the following: 1. Start an appliance with test.img as a disk. 2. Format test.img with ext2. 3. Create a file /test 4. Write 256M of data to /test in 2M chunks Only step 4 is timed. I ran the program against test.img prepared in 4 different ways: 1. A sparse raw file: 15.3 seconds truncate --size 300M test.img 2. A preallocated raw file: 14.8 seconds fallocate -l 300M test.img 3. A sparse qcow2 file: 223.0 seconds qemu-img create -f qcow2 test.img 300M 4. A metadata preallocated qcow2 file: 14.5 seconds qemu-img create -f qcow2 -o preallocated=metadata test.img 300M With the exception of (3), I ran the test 3 times and took the middle time rounded to 1DP. I saw about 5-10% variation. I only ran the test against (3) once. The precise ordering of 1, 2 and 4 is surprising, but given the variation probably not that interesting: they're all about the same. The interesting thing is that the overhead of qcow2 metadata creation during the test seems to account for a 15x performance penalty. I had a cursory look at metadata preallocation, which I hadn't been aware of before today. Creating a qcow2 image of any size with no preallocation results in a 136k file. If you preallocate the metadata, a sparse file is created large enough to accomodate the entire image, with >136k actually used. In the above 300M case this is 204k. On a slightly more practical 20G image, 3.3M is preallocated. It's also worth noting that the image takes considerably longer to create. On my laptop, creation without preallocation is 'instantaneous' at any size. With preallocation, a 20G image takes 6 seconds to create, and a 100G image takes 26 seconds. libvirt's qemu driver doesn't currently preallocate qcow2 metadata when creating a new image. Given the tiny disk space overhead of the metadata (0.02%) and the small processing overhead of pre-creation relative to subsequent creation on-the-fly, I suggest that the libvirt qemu driver is updated to pre-allocate metadata by default. Thoughts? Matt [1] Note that I'm running this against libguestfs from git, which uses virtio-serial rather than usermode networking for appliance<->host communication. This change alone improved the performance of this test by about 10x. If your numbers don't match mine, that's probably why. I don't know off the top of my head if this change has made it into F14 yet. It's definitely not in F13. -- Matthew Booth, RHCA, RHCSS Red Hat Engineering, Virtualisation Team GPG ID: D33C3490 GPG FPR: 3733 612D 2D05 5458 8A8A 1600 3441 EA19 D33C 3490

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[libvirt] New PHP bindings
by Arnar Mar Sig 03 Nov '10

03 Nov '10

Hi There are few PHP libvirt bindings out there, but all I found are procedural based and incomplete. To address this I created another binding that is OO based and in large part generated from libvirt-api.xml. The extension already supports most of the API, split into 6 classes: virConnect, virDomain, virInterface, virNetwork, virStoragePool, and virStorageVol. Snapshot of the current code can be found at: http://libvirt-debian.vm.antab.is/files/php-libvirt.tar.bz2 Or using svn from: http://svn.antab.is/php-libvirt/trunk Build instructions are in the README file. Documents can be found at http://libvirt-debian.vm.antab.is/ NOTE: Most of the docs are copied from libvirt. It has mostly been tested with libvirt test backend and PHP unit tests (phpt) are used to test, covering about 40% of basic usage. It is by no means complete and missing some functionality like classmaps (So virConnect::domainLookupBy* can return user defined class extended from virDomain) and probably leaks memory. I would appreciate any input and comments. Thanks Arnar Mar Sig

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[libvirt] [PATCH 00/10] Allow access to text console with virStream APIs (v2)
by Daniel P. Berrange 02 Nov '10

02 Nov '10

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