Réf. : Re: [Libvir] Re: Proposal : add 3 functions to Libvirt API, for virtual CPUs
by jean-paul.pigache＠bull.net
I hope I will find a way to post the patches prepared by Michel Ponceau
before the end of the week.
Jean-Paul
"Daniel P. Berrange" <berrange(a)redhat.com>
Envoyé par : libvir-list-bounces(a)redhat.com
29/07/2006 09:35
Veuillez répondre à "Daniel P. Berrange"
Pour : Jim Fehlig <jfehlig(a)novell.com>
cc : libvir-list(a)redhat.com
Objet : Re: [Libvir] Re: Proposal : add 3 functions to Libvirt API, for
virtual CPUs
On Fri, Jul 28, 2006 at 03:18:17PM -0600, Jim Fehlig wrote:
> Has any progress been made on this proposal? I don't see anything in
> current CVS. This functionality would be useful for Xen-CIM project.
IIRC Michel Ponceau might have started on some prototype code, but he
didn't post it to the list yet & is apparently on vacation for another
couple of weeks (according to his email auto-responder). If no one else
has started work on it in the meantime, I'm planning to get working on
it when I return from vacation Aug 4th since I also need it for the
virt-manager application.
Regards,
Dan.
> michel.ponceau(a)bull.net wrote:
> >
> >Corrections on proposal:
> >1) PinVcpus
> >Replace:
> > * @cpumap: pointer to a bit map of real CPUs (format in virVcpuInfo)
> >* @maplen: length of cpumap, in 8-bit bytes
> >by:
> > * @cpumap: pointer to a bit map of real CPUs (in 8-bit bytes).
> > * Each bit set to 1 means that corresponding CPU is usable.
> > * Bytes are stored in little-endian order: CPU0-7, 8-15...
> > * In each byte, lowest CPU number is least significant bit.
> > * @maplen: number of bytes in cpumap, from 1 up to size of CPU map in
> > * underlying virtualization system (Xen...).
> > * If maplen < size, missing bytes are set to zero.
> > * If maplen > size, failure code is returned.
> >
> >2) GetVcpu
> >Add 4rth argument:
> > * @maplen: number of bytes in cpumap field of virVcpuInfo
> >virDomainGetVcpus(virDomainPtr domain, virVcpuInfoPtr info, int
> >maxinfo, int maplen)
> >
> >3) Structure VcpuInfo
> >Suppress: #define VIR_MAX_CPUS 256
> >Replace:
> > unsigned char cpumap[VIR_MAX_CPUS/8]; /* Bit map of usable real
CPUs.
> >by:
> > unsigned char cpumap[]; /* Bit map of usable real CPUs.
> > Variable length: it may be less or greater than size of CPU
> >map in
> > underlying virtualization system (Xen...).
> >
> >4) Accessor macros: to be defined later.
> >
> >Veuillez répondre à veillard(a)redhat.com
> >
> >Pour : michel.ponceau(a)bull.net
> >cc : libvir-list(a)redhat.com
> >Objet : Re: Proposal : add 3 functions to Libvirt API, for
> >virtual CPUs
> >
> >On Fri, Jun 30, 2006 at 04:00:45PM +0200, michel.ponceau(a)bull.net
wrote:
> >> For our administration, we need the following actions, while
concerned
> >> domain is running:
> >> 1) Change the number of virtual CPUs.
> >> 2) Change the pinning (affinity) of a virtual CPU on real CPUs.
> >> 3) Get detailed information for each virtual CPU.
> >> Currently there is no Libvirt function provided for that. We suggest
to
> >> add the following 3 functions (in libvirt.c):
> >> /**
> >> * virDomainSetVcpus:
> >> * @domain: pointer to domain object, or NULL for Domain0
> >> * @nvcpus: the new number of virtual CPUs for this domain
> >> *
> >> * Dynamically change the number of virtual CPUs used by the domain.
> >> * Note that this call may fail if the underlying virtualization
> >> hypervisor
> >> * does not support it or if growing the number is arbitrary limited.
> >> * This function requires priviledged access to the hypervisor.
> >> *
> >> * Returns 0 in case of success, -1 in case of failure.
> >> */
> >> int virDomainSetVcpus(virDomainPtr domain, unsigned int nvcpus)
> >
> > okay
> >
> >> /**
> >> * virDomainPinVcpu:
> >> * @domain: pointer to domain object, or NULL for Domain0
> >> * @vcpu: virtual CPU number
> >> * @cpumap: pointer to a bit map of real CPUs (format in virVcpuInfo)
> >> * @maplen: length of cpumap, in 8-bit bytes
> >> *
> >> * Dynamically change the real CPUs which can be allocated to a
virtual
> >> CPU.
> >> * This function requires priviledged access to the hypervisor.
> >> *
> >> * Returns 0 in case of success, -1 in case of failure.
> >> */
> >> int virDomainPinVcpu(virDomainPtr domain, unsigned int vcpu,
> >> unsigned char *cpumap, int maplen)
> >
> > Can you explain more clearly what is the format of cpumap ? An example
> >would be welcome, and that would be needed for the doc and maybe
testing.
> >What would happen if maplen is < or > than the number of CPU divided
> >by 8 ?
> >
> >> /**
> >> * virDomainGetVcpus:
> >> * @domain: pointer to domain object, or NULL for Domain0
> >> * @info: pointer to an array of virVcpuInfo structures
> >> * @maxinfo: number of structures in info array
> >> *
> >> * Extract information about virtual CPUs of a domain, store it in
info
> >> array.
> >> *
> >> * Returns the number of info filled in case of success, -1 in case
of
> >> failure.
> >> */
> >> int virDomainGetVcpus(virDomainPtr domain, virVcpuInfoPtr info, int
> >> maxinfo)
> >
> > Hum ... now the problem with that API entry point is that we 'burn'
the
> >maximum 256 processors in the ABI, i.e. if we ever need to go past 256
> >client and servers need to be recompiled. Maybe this is not a real
problem
> >in practice but that's annoying. Is there existing APIs doing this kind
> >of things (in POSIX for example), and what hard limit did they use ?
> > Maybe
> > int virDomainGetVcpusNr(virDomainPtr domain, int nr, virVcpuInfoPtr
info,
> > int maxCPU);
> >Where the maxCPU is defined by the client as the number of real CPU
> >it defined in its virVcpuInfoPtr and then an iteration over the virtual
> >CPU defined in the domain is possible too.
> >Of course if the domain uses many virtual CPUs this would become
expensive
> >but somehow I don't see that being the common use, I would rather guess
> >the domains created use a few CPUs even if instantiated on a very
> >large machine.
> >This
> >
> >
> >> with the following structure (in libvirt.h):
> >> /**
> >> * virVcpuInfo: structure for information about a virtual CPU in a
> >domain.
> >> */
> >> #define VIR_MAX_CPUS 256
> >
> > Hum, there is already NUMA machines with more than 256 processors,
> >it's annoying to define an API limit when you know it is already
> >breakable.
> >
> >> typedef enum {
> >> VIR_VCPU_OFFLINE = 0, /* the virtual CPU is offline */
> >> VIR_VCPU_RUNNING = 1, /* the virtual CPU is running */
> >> VIR_VCPU_BLOCKED = 2, /* the virtual CPU is blocked on
> >resource
> >> */
> >> } virVcpuState;
> >>
> >> typedef struct _virVcpuInfo virVcpuInfo;
> >> struct _virVcpuInfo {
> >> unsigned int number; /* virtual CPU number */
> >> int state; /* value from virVcpuState */
> >> unsigned long long cpuTime; /* CPU time used, in nanoseconds */
> >> int cpu; /* real CPU number, or -1 if offline
*/
> >> unsigned char cpumap[VIR_MAX_CPUS/8]; /* Bit map of usable real
> >CPUs.
> >> Each bit set to 1 means that corresponding CPU is
> >usable.
> >> Bytes are stored in little-endian order: CPU0-7,
8-15...
> >> In each byte, lowest CPU number is least significant
> >bit
> >> */
> >> };
> >> typedef virVcpuInfo *virVcpuInfoPtr;
> >
> > Hum, maybe some accessors should be provided in the API, letting the
> >client
> >code handle access and having to take care of indianness issues
> >doesn't feel
> >very nice. Something like the FD_CLR/FD_ISSET/FD_SET/FD_ZERO
equivalents
> >when using the select() POSIx call.
> >
> >> I have successfully tried those functions via Xen hypervisor, except
> >for
> >> the first (SetVcpus) where hypervisor operation DOM0_MAX_VCPUS fails
> >> (maybe it is not possible on a running domain ?). That function was
> >> successful via Xen daemon.
> >
> >Maybe that operation requires more than one hypervisor call to
> >actually enable
> >the processors. The simpler would be to look at the code in xend about
> >what's
> >needed there, maybe the kernel need to be made aware of that and I
> >would expect
> >this to be a xenstore operation.
> >At least we know we can fallback to xend if the hypervisor call
> >doesn't work
> >directly.
> >I don't know if virDomainGetVcpus should really be mutated into
> >virDomainGetVcpusNr, I would certainly like to be able to keep that API
> >extensible for more than 256 CPUs. Maybe I'm just too cautious there,
> >
> > I would really like feedback from others on this issue !
> >In the meantime sending the current set of patches you developped could
> >allow to look closely at the 2 calls that I feel okay with.
> >
> > thanks and sorry it took so long !
> >
> >Daniel
> >
> >--
> >Daniel Veillard | Red Hat http://redhat.com/
> >veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/
> >http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/
> >
>
>------------------------------------------------------------------------
> >
> >--
> >Libvir-list mailing list
> >Libvir-list(a)redhat.com
> >https://www.redhat.com/mailman/listinfo/libvir-list
> >
>
> --
> Libvir-list mailing list
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> https://www.redhat.com/mailman/listinfo/libvir-list
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18 years, 5 months
[Libvir] Re: Proposal : add 3 functions to Libvirt API, for virtual CPUs
by michel.ponceau＠bull.net
Corrections on proposal:
1) PinVcpus
Replace:
* @cpumap: pointer to a bit map of real CPUs (format in virVcpuInfo)
* @maplen: length of cpumap, in 8-bit bytes
by:
* @cpumap: pointer to a bit map of real CPUs (in 8-bit bytes).
* Each bit set to 1 means that corresponding CPU is usable.
* Bytes are stored in little-endian order: CPU0-7, 8-15...
* In each byte, lowest CPU number is least significant bit.
* @maplen: number of bytes in cpumap, from 1 up to size of CPU map in
* underlying virtualization system (Xen...).
* If maplen < size, missing bytes are set to zero.
* If maplen > size, failure code is returned.
2) GetVcpu
Add 4rth argument:
* @maplen: number of bytes in cpumap field of virVcpuInfo
virDomainGetVcpus(virDomainPtr domain, virVcpuInfoPtr info, int maxinfo,
int maplen)
3) Structure VcpuInfo
Suppress: #define VIR_MAX_CPUS 256
Replace:
unsigned char cpumap[VIR_MAX_CPUS/8]; /* Bit map of usable real CPUs.
by:
unsigned char cpumap[]; /* Bit map of usable real CPUs.
Variable length: it may be less or greater than size of CPU map in
underlying virtualization system (Xen...).
4) Accessor macros: to be defined later.
Veuillez répondre à veillard(a)redhat.com
Pour : michel.ponceau(a)bull.net
cc : libvir-list(a)redhat.com
Objet : Re: Proposal : add 3 functions to Libvirt API, for virtual CPUs
On Fri, Jun 30, 2006 at 04:00:45PM +0200, michel.ponceau(a)bull.net wrote:
> For our administration, we need the following actions, while concerned
> domain is running:
> 1) Change the number of virtual CPUs.
> 2) Change the pinning (affinity) of a virtual CPU on real CPUs.
> 3) Get detailed information for each virtual CPU.
> Currently there is no Libvirt function provided for that. We suggest to
> add the following 3 functions (in libvirt.c):
> /**
> * virDomainSetVcpus:
> * @domain: pointer to domain object, or NULL for Domain0
> * @nvcpus: the new number of virtual CPUs for this domain
> *
> * Dynamically change the number of virtual CPUs used by the domain.
> * Note that this call may fail if the underlying virtualization
> hypervisor
> * does not support it or if growing the number is arbitrary limited.
> * This function requires priviledged access to the hypervisor.
> *
> * Returns 0 in case of success, -1 in case of failure.
> */
> int virDomainSetVcpus(virDomainPtr domain, unsigned int nvcpus)
okay
> /**
> * virDomainPinVcpu:
> * @domain: pointer to domain object, or NULL for Domain0
> * @vcpu: virtual CPU number
> * @cpumap: pointer to a bit map of real CPUs (format in virVcpuInfo)
> * @maplen: length of cpumap, in 8-bit bytes
> *
> * Dynamically change the real CPUs which can be allocated to a virtual
> CPU.
> * This function requires priviledged access to the hypervisor.
> *
> * Returns 0 in case of success, -1 in case of failure.
> */
> int virDomainPinVcpu(virDomainPtr domain, unsigned int vcpu,
> unsigned char *cpumap, int maplen)
Can you explain more clearly what is the format of cpumap ? An example
would be welcome, and that would be needed for the doc and maybe testing.
What would happen if maplen is < or > than the number of CPU divided by 8
?
> /**
> * virDomainGetVcpus:
> * @domain: pointer to domain object, or NULL for Domain0
> * @info: pointer to an array of virVcpuInfo structures
> * @maxinfo: number of structures in info array
> *
> * Extract information about virtual CPUs of a domain, store it in info
> array.
> *
> * Returns the number of info filled in case of success, -1 in case of
> failure.
> */
> int virDomainGetVcpus(virDomainPtr domain, virVcpuInfoPtr info, int
> maxinfo)
Hum ... now the problem with that API entry point is that we 'burn' the
maximum 256 processors in the ABI, i.e. if we ever need to go past 256
client and servers need to be recompiled. Maybe this is not a real problem
in practice but that's annoying. Is there existing APIs doing this kind
of things (in POSIX for example), and what hard limit did they use ?
Maybe
int virDomainGetVcpusNr(virDomainPtr domain, int nr, virVcpuInfoPtr
info,
int maxCPU);
Where the maxCPU is defined by the client as the number of real CPU
it defined in its virVcpuInfoPtr and then an iteration over the virtual
CPU defined in the domain is possible too.
Of course if the domain uses many virtual CPUs this would become expensive
but somehow I don't see that being the common use, I would rather guess
the domains created use a few CPUs even if instantiated on a very large
machine.
This
> with the following structure (in libvirt.h):
> /**
> * virVcpuInfo: structure for information about a virtual CPU in a
domain.
> */
> #define VIR_MAX_CPUS 256
Hum, there is already NUMA machines with more than 256 processors,
it's annoying to define an API limit when you know it is already
breakable.
> typedef enum {
> VIR_VCPU_OFFLINE = 0, /* the virtual CPU is offline */
> VIR_VCPU_RUNNING = 1, /* the virtual CPU is running */
> VIR_VCPU_BLOCKED = 2, /* the virtual CPU is blocked on
resource
> */
> } virVcpuState;
>
> typedef struct _virVcpuInfo virVcpuInfo;
> struct _virVcpuInfo {
> unsigned int number; /* virtual CPU number */
> int state; /* value from virVcpuState */
> unsigned long long cpuTime; /* CPU time used, in nanoseconds */
> int cpu; /* real CPU number, or -1 if offline */
> unsigned char cpumap[VIR_MAX_CPUS/8]; /* Bit map of usable real
CPUs.
> Each bit set to 1 means that corresponding CPU is
usable.
> Bytes are stored in little-endian order: CPU0-7, 8-15...
> In each byte, lowest CPU number is least significant bit
> */
> };
> typedef virVcpuInfo *virVcpuInfoPtr;
Hum, maybe some accessors should be provided in the API, letting the
client
code handle access and having to take care of indianness issues doesn't
feel
very nice. Something like the FD_CLR/FD_ISSET/FD_SET/FD_ZERO equivalents
when using the select() POSIx call.
> I have successfully tried those functions via Xen hypervisor, except for
> the first (SetVcpus) where hypervisor operation DOM0_MAX_VCPUS fails
> (maybe it is not possible on a running domain ?). That function was
> successful via Xen daemon.
Maybe that operation requires more than one hypervisor call to actually
enable
the processors. The simpler would be to look at the code in xend about
what's
needed there, maybe the kernel need to be made aware of that and I would
expect
this to be a xenstore operation.
At least we know we can fallback to xend if the hypervisor call doesn't
work
directly.
I don't know if virDomainGetVcpus should really be mutated into
virDomainGetVcpusNr, I would certainly like to be able to keep that API
extensible for more than 256 CPUs. Maybe I'm just too cautious there,
I would really like feedback from others on this issue !
In the meantime sending the current set of patches you developped could
allow to look closely at the 2 calls that I feel okay with.
thanks and sorry it took so long !
Daniel
--
Daniel Veillard | Red Hat http://redhat.com/
veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/
18 years, 5 months
[Libvir] Source repository
by Diwaker Gupta
Given that most Xen related stuff (including virt-man) lives in
Mercurial repositories, it seems a little weird (and a little
cumbersome) that libvirt continues to use CVS. This issue briefly came
up on the list once earlier, but didn't go anywhere. Is there any
strong reason why libvirt can't move to Mercurial?
Diwaker
--
Web/Blog/Gallery: http://floatingsun.net/blog
18 years, 5 months
Réf. : Re: [Libvir] Re: Proposal : add 3 functions to Libvirt API, for virtual CPUs
by jean-paul.pigache＠bull.net
This interesting thread is temporarilu suspended because Michel has left
for some (long) vacation until August 15th.
I think the last proposal is a good one and deserves to be implemented and
tested.
I am confident that Michel will be willing to update its patch accordingly
when he comes back.
Is it OK for you ?.
Side question: is there a defined "sign-off" procedure to follow when
submitting patches ?
Cordialement.
Jean-Paul
Daniel Veillard <veillard(a)redhat.com>
Envoyé par : libvir-list-bounces(a)redhat.com
17/07/2006 15:08
Veuillez répondre à veillard
Pour : "Daniel P. Berrange" <berrange(a)redhat.com>
cc : libvir-list(a)redhat.com, michel.ponceau(a)bull.net
Objet : Re: [Libvir] Re: Proposal : add 3 functions to Libvirt API, for
virtual CPUs
On Mon, Jul 17, 2006 at 01:50:25PM +0100, Daniel P. Berrange wrote:
> On Tue, Jul 11, 2006 at 10:50:53AM -0400, Daniel Veillard wrote:
> > We still have a relatively simple API for the common case, and for
special
> > cases we have an extension capability with relatively clear
definitions. it's
> > a bitstrange but I think that should cover most case as best as
possible
>
> I dont particularly like this as an API because I think it will be error
> prone for application developers. Most app developers will only ever
have
> a handful of CPUs in their test machines, so they'll never the alternate
> codepath for > 256 cpu case. Likewise I don't like the idea of a
virVcpuInfo
> struct which has a variable size because it will totally confuse people
who
> haven't read the API docs very carefully, again leading to obscure bugs.
>
> The root problem is that we have two conflicting goals here
>
> 1. Want to have virVcpuInfo be a fixed size struct
> 2. We want a cpumap of arbitrary size
Right this is confusing, I wanted to avoid another allocation in the
general
case but this made things even more confusing.
> The obvious solution to this problem is to *remove* the cpumap data
from
> the virVcpuInfo structure completely, and always pass in a separately
> malloc'd array of the correct size. So I'd suggest:
>
> typedef struct _virVcpuInfo virVcpuInfo;
> struct _virVcpuInfo {
> unsigned int number; /* virtual CPU number */
> int state; /* value from virVcpuState */
> unsigned long long cpuTime; /* CPU time used, in nanoseconds */
> int cpu; /* real CPU number, or -1 if offline */
> }
>
> virDomainGetVcpus(virDomainPtr domain, virVcpuInfoPtr info, int
maxinfo,
> char *cpumap, int maplen);
Agreed, this is the most logical approach
>
> The client applications calling this API already have to malloc() the
memory
> region for the 'info' parameter of a correct size, so having to also
malloc
> the cpumap parameter is no extra trouble.
>
> virDomainInfo info;
> virDomainVpuInfoPtr cpuInfo;
> int cpuMapLen;
> char *cpuMap;
>
> virDomainGetInfo(domain, &info);
>
> cpuInfo = malloc(sizeof(virDomainVcpuInfo)*info.nrVirtCpu);
> cpuMapLen = (info.nrVirtCpu + 7) / 8 ;
> cpuMap = malloc(cpuMapLen);
>
> virDomainGetVCpus(domain, cpuInfo, info.nrVirtCpu, cpuMap, cpuMapLen);
>
> ... do stuff with the data ...
>
> free(cpuInfo);
> free(cpuMap);
>
>
> So you can see there is minimal extra work to always pass in cpuMap as
> a separate parameter. If an application didn't care about the cpuMap
> data they could simply pass in NULL.
Agree. We should keep an example of use (like above completed) in the
source
tree to help developpers.
Daniel
--
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veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/
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18 years, 5 months
[Libvir] Bug with libvirt in Xen 3.0.1?
by pvetere＠redhat.com
Hi, I think I may have found a bug in libvirt and wanted see what people
thought. I'm using the stock FC5 installation at the moment (with xen 3.0.1),
and the newest version of libvirt. I am noticing that with xen 3.0.1 and newer
versions of libvirt, getDomainsID() seems to return bogus values. For example:
[root@test05 ~]# virsh list
Id Name State
----------------------------------
0 Domain-0 running
libvir: Xen Daemon error : GET operation failed: No such domain 65486
libvir: Xen Daemon error : GET operation failed: No such domain 2986
But, if I use xm, I get what I expect:
[root@test05 ~]# xm list
Name ID Mem(MiB) VCPUs State Time(s)
Domain-0 0 1507 2 r----- 387.5
vm1 1 256 1 -b---- 151.3
vm2 2 256 1 -b---- 87.9
After some digging around in the code, I believe that libvirt is incorrectly
identifying the hypervisor as being "old" in xen_internal.c:xenHypervisorInit,
and is therefore passing the incorrect parameter structure into the hypervisor
when it makes its ioctl in xen_internal.c:xenHypervisorListDomains.
I've tried this same test on a system running xen 3.0.2, and as I expected
everything works fine. So, there must be something different about xen 3.0.1
that libvirt is not accounting for.
At this point, I don't really have more time to dig further but I thought I'd
bring up the issue in case someone on this list can offer more insight.
Pete
18 years, 5 months
[Libvir] Virtual Machine Manager 0.1.5 release
by Daniel P. Berrange
I've just pushed out another snapshot of the Virtual Machine Manager GUI
application for managing Xen machines via libvirt.
A summary of the changes in this 0.1.5 release[1]:
* Integration with GNOME keyring for the VNC console to avoid
need to remember passwords when accessing the guest domain's
console
* Use cairo to render a '50% alpha gray wash' over the screenshot
to give appearance of a 'dimmed' display when paused. Also render
the word 'paused' in big letters.
* Initial cut of code for saving & restoring domain snapshots to disk
* Added icons for buttons which were missing graphics
* Miscellaneous RPM spec file fixes to comply with rpmlint
* Update status icons to match those in the gnome-applet-vm
* Added domain ID and # VCPUs to summary view
* Misc bug fixes
The next priority target for development is some UI for creating new
VM instances (a GUI equivalent of xenguest-install.py script shipping
with current Fedora Xen packages) and implenenting the UI for editing
domain configuration / hardware.
In addition there is now a more permanent home for the application's
web pages:
http://virt-manager.et.redhat.com/index.html
And the Mercurial repository is now published for anonymous read-only
access at:
http://hg.et.redhat.com/virt/applications/virt-manager--devel
Patches are welcome either as traditional unified diffs, or as mercurial
changeset bundles - see the following page for details on exporting bundles
using hg:
http://virt-manager.et.redhat.com/scmrepo.html
Regards,
Dan.
[1] There was a 0.1.4 but it had a fatal flaw in it breaking the console
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18 years, 5 months
[Libvir] Question about XML
by Juan Walker
Hi,
I have a question regarding the XML format that libvir uses for domain configuration.
I was wondering if there is a way to use the configuration format that xm uses or if a tool exists to convert to XML. I'm writing an app to help users manage their Xen domains but I'm hoping to be able to use any .sxp files that the user already has.
I suspect I missed something in the documentation about why the XML format is better, but if there is no such tool maybe I should volunteer to write one?
Thanks.
18 years, 5 months
[Libvir] just a question about libvirt evolution
by Philippe Berthault
Hello,
Several major modifications will appear this year in future Xen releases
(3.0.3 and 3.0.4) that may have impacts on libvirt. These modifications
(see xen roadmap edited by Ian Pratt in july 2006) are :
- Introduction of XML-RPC,
- Xen configuration files in XML format,
- Suppression of S-Expressions,
- etc..
What is the libvirt position about these points ?
Is the initial goal of libvirt to mask Xen evolutions will be always
possible ?
The most problematic problem would be the configurations files in XML
format. Libvirt already supports its own XML format of configuration
files. It seems to me that it would be interesting to use the same XML
format (or a compatible format) in libvirt and in Xen. Is there a plan
in this direction ?
Thanks.
18 years, 5 months
[Libvir] possible bug in virDomainLookupByID
by Bryan D. Payne
I'm experiencing an odd problem in virDomainLookupByID when using 0.1.3
that does not exist when using 0.1.1. Perhaps this is a side effect of
switching the backend connection? I'm curious is anyone else has seen
this and/or if you have any suggestions for fixing it.
The attached code generates the problem that I'm seeing. Specifically,
after upgrading to 0.1.3, calling virDomainLookupByID twice results in a
failure on the second call. This behavior was not seen in 0.1.1. Any
thoughts?
Thanks,
bryan
PS... This problem is seen in XenAccess. Thanks to Daniele Sgandurra for
bringing it to my attention.
#include <stdio.h>
#include <string.h>
#include <libvirt/libvirt.h>
#include <libvirt/virterror.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
char *get_xml_info (int id)
{
virConnectPtr conn = NULL;
virDomainPtr dom = NULL;
char *xml_data = NULL;
/* NULL means connect to local Xen hypervisor */
conn = virConnectOpenReadOnly(NULL);
if (NULL == conn) {
printf("ERROR: Failed to connect to hypervisor\n");
goto error_exit;
}
/* Find the domain of the given id */
dom = virDomainLookupByID(conn, id);
if (NULL == dom) {
virErrorPtr error = virConnGetLastError(conn);
printf("(%d) %s\n", error->code, error->message);
printf("ERROR: Failed to find Domain %d\n", id);
goto error_exit;
}
xml_data = virDomainGetXMLDesc(dom, 0);
error_exit:
if (NULL!= dom) virDomainFree(dom);
if (NULL!= conn) virConnectClose(conn);
return xml_data;
}
int main ()
{
char *xml = NULL;
xml = get_xml_info(1);
if (!xml){
printf("Failed on first try\n");
return 0;
}
free(xml);
xml = get_xml_info(1);
if (!xml){
printf("Failed on second try\n");
return 0;
}
free(xml);
return 1;
}
18 years, 5 months
